Merge changes I66527dd1,Iafcfe3f2,I1f7d77fc,I8a75c32a

* changes:
  GetMergeList: Also allow caching of responses for non-merges
  Include a magic /MERGE_LIST file for merge commits
  Patch: Add static method to check if file is magic
  Don't compare commit message against auto-merge commit

gerrit-acceptance-framework/src/test/java/com/google/gerrit/acceptance/AbstractDaemonTest.java

@@ -17,6 +17,8 @@ package com.google.gerrit.acceptance;
 import static com.google.common.truth.Truth.assertThat;
 import static com.google.gerrit.acceptance.GitUtil.initSsh;
 import static com.google.gerrit.extensions.api.changes.SubmittedTogetherOption.NON_VISIBLE_CHANGES;
+import static com.google.gerrit.reviewdb.client.Patch.COMMIT_MSG;
+import static com.google.gerrit.reviewdb.client.Patch.MERGE_LIST;
 import static com.google.gerrit.server.group.SystemGroupBackend.REGISTERED_USERS;
 import static org.eclipse.jgit.lib.Constants.HEAD;
 
@@ -48,6 +50,8 @@ import com.google.gerrit.extensions.client.ListChangesOption;
 import com.google.gerrit.extensions.client.SubmitType;
 import com.google.gerrit.extensions.common.ActionInfo;
 import com.google.gerrit.extensions.common.ChangeInfo;
+import com.google.gerrit.extensions.common.ChangeType;
+import com.google.gerrit.extensions.common.DiffInfo;
 import com.google.gerrit.extensions.common.EditInfo;
 import com.google.gerrit.extensions.restapi.BinaryResult;
 import com.google.gerrit.extensions.restapi.IdString;
@@ -67,6 +71,7 @@ import com.google.gerrit.server.account.AccountCache;
 import com.google.gerrit.server.account.GroupCache;
 import com.google.gerrit.server.change.Abandon;
 import com.google.gerrit.server.change.ChangeResource;
+import com.google.gerrit.server.change.FileContentUtil;
 import com.google.gerrit.server.change.RevisionResource;
 import com.google.gerrit.server.change.Revisions;
 import com.google.gerrit.server.config.AllProjectsName;
@@ -546,21 +551,26 @@ public abstract class AbstractDaemonTest {
 
   protected PushOneCommit.Result createMergeCommitChange(String ref)
       throws Exception {
+    return createMergeCommitChange(ref, "foo");
+  }
+
+  protected PushOneCommit.Result createMergeCommitChange(String ref, String file)
+      throws Exception {
     ObjectId initial = repo().exactRef(HEAD).getLeaf().getObjectId();
 
     PushOneCommit.Result p1 = pushFactory.create(db, admin.getIdent(),
-        testRepo, "parent 1", ImmutableMap.of("foo", "foo-1", "bar", "bar-1"))
+        testRepo, "parent 1", ImmutableMap.of(file, "foo-1", "bar", "bar-1"))
         .to(ref);
 
     // reset HEAD in order to create a sibling of the first change
     testRepo.reset(initial);
 
     PushOneCommit.Result p2 = pushFactory.create(db, admin.getIdent(),
-        testRepo, "parent 2", ImmutableMap.of("foo", "foo-2", "bar", "bar-2"))
+        testRepo, "parent 2", ImmutableMap.of(file, "foo-2", "bar", "bar-2"))
         .to(ref);
 
     PushOneCommit m = pushFactory.create(db, admin.getIdent(), testRepo, "merge",
-        ImmutableMap.of("foo", "foo-1", "bar", "bar-2"));
+        ImmutableMap.of(file, "foo-1", "bar", "bar-2"));
     m.setParents(ImmutableList.of(p1.getCommit(), p2.getCommit()));
     PushOneCommit.Result result = m.to(ref);
     result.assertOkStatus();
@@ -1086,4 +1096,45 @@ public abstract class AbstractDaemonTest {
     }
     assertThat(refValues.keySet()).containsAnyIn(trees.keySet());
   }
+
+  protected void assertDiffForNewFile(DiffInfo diff, RevCommit commit,
+      String path, String expectedContentSideB) throws Exception {
+    List<String> expectedLines = new ArrayList<>();
+    for (String line : expectedContentSideB.split("\n")) {
+      expectedLines.add(line);
+    }
+
+    assertThat(diff.binary).isNull();
+    assertThat(diff.changeType).isEqualTo(ChangeType.ADDED);
+    assertThat(diff.diffHeader).isNotNull();
+    assertThat(diff.intralineStatus).isNull();
+    assertThat(diff.webLinks).isNull();
+
+    assertThat(diff.metaA).isNull();
+    assertThat(diff.metaB).isNotNull();
+    assertThat(diff.metaB.commitId).isEqualTo(commit.name());
+
+    String expectedContentType = "text/plain";
+    if (COMMIT_MSG.equals(path)) {
+      expectedContentType = FileContentUtil.TEXT_X_GERRIT_COMMIT_MESSAGE;
+    } else if (MERGE_LIST.equals(path)) {
+      expectedContentType = FileContentUtil.TEXT_X_GERRIT_MERGE_LIST;
+    }
+    assertThat(diff.metaB.contentType).isEqualTo(expectedContentType);
+
+    assertThat(diff.metaB.lines).isEqualTo(expectedLines.size());
+    assertThat(diff.metaB.name).isEqualTo(path);
+    assertThat(diff.metaB.webLinks).isNull();
+
+    assertThat(diff.content).hasSize(1);
+    DiffInfo.ContentEntry contentEntry = diff.content.get(0);
+    assertThat(contentEntry.b).containsExactlyElementsIn(expectedLines)
+        .inOrder();
+    assertThat(contentEntry.a).isNull();
+    assertThat(contentEntry.ab).isNull();
+    assertThat(contentEntry.common).isNull();
+    assertThat(contentEntry.editA).isNull();
+    assertThat(contentEntry.editB).isNull();
+    assertThat(contentEntry.skip).isNull();
+  }
 }

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/api/change/GetMergeListIT.java

@@ -1,80 +0,0 @@
-// Copyright (C) 2016 The Android Open Source Project
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package com.google.gerrit.acceptance.api.change;
-
-import static com.google.common.truth.Truth.assertThat;
-import static org.eclipse.jgit.lib.Constants.HEAD;
-
-import com.google.common.collect.ImmutableList;
-import com.google.common.collect.ImmutableMap;
-import com.google.gerrit.acceptance.AbstractDaemonTest;
-import com.google.gerrit.acceptance.NoHttpd;
-import com.google.gerrit.acceptance.PushOneCommit;
-import com.google.gerrit.extensions.common.CommitInfo;
-
-import org.eclipse.jgit.lib.ObjectId;
-import org.junit.Test;
-
-import java.util.List;
-
-@NoHttpd
-public class GetMergeListIT extends AbstractDaemonTest {
-
-  @Test
-  public void getMergeList() throws Exception {
-    ObjectId initial = repo().exactRef(HEAD).getLeaf().getObjectId();
-
-    PushOneCommit.Result gp1 = pushFactory
-        .create(db, admin.getIdent(), testRepo, "grand parent 1",
-            ImmutableMap.of("foo", "foo-1.1", "bar", "bar-1.1"))
-        .to("refs/for/master");
-
-    PushOneCommit.Result p1 = pushFactory
-        .create(db, admin.getIdent(), testRepo, "parent 1",
-            ImmutableMap.of("foo", "foo-1.2", "bar", "bar-1.2"))
-        .to("refs/for/master");
-
-    // reset HEAD in order to create a sibling of the first change
-    testRepo.reset(initial);
-
-    PushOneCommit.Result gp2 = pushFactory
-        .create(db, admin.getIdent(), testRepo, "grand parent 1",
-            ImmutableMap.of("foo", "foo-2.1", "bar", "bar-2.1"))
-        .to("refs/for/master");
-
-    PushOneCommit.Result p2 = pushFactory
-        .create(db, admin.getIdent(), testRepo, "parent 2",
-            ImmutableMap.of("foo", "foo-2.2", "bar", "bar-2.2"))
-        .to("refs/for/master");
-
-    PushOneCommit m = pushFactory.create(db, admin.getIdent(), testRepo,
-        "merge", ImmutableMap.of("foo", "foo-1", "bar", "bar-2"));
-    m.setParents(ImmutableList.of(p1.getCommit(), p2.getCommit()));
-    PushOneCommit.Result result = m.to("refs/for/master");
-    result.assertOkStatus();
-
-    List<CommitInfo> mergeList =
-        gApi.changes().id(result.getChangeId()).current().getMergeList().get();
-    assertThat(mergeList).hasSize(2);
-    assertThat(mergeList.get(0).commit).isEqualTo(p2.getCommit().name());
-    assertThat(mergeList.get(1).commit).isEqualTo(gp2.getCommit().name());
-
-    mergeList = gApi.changes().id(result.getChangeId()).current().getMergeList()
-        .withUninterestingParent(2).get();
-    assertThat(mergeList).hasSize(2);
-    assertThat(mergeList.get(0).commit).isEqualTo(p1.getCommit().name());
-    assertThat(mergeList.get(1).commit).isEqualTo(gp1.getCommit().name());
-  }
-}

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/api/change/MergeListIT.java

@@ -0,0 +1,209 @@
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.acceptance.api.change;
+
+import static com.google.common.collect.Iterables.getOnlyElement;
+import static com.google.common.truth.Truth.assertThat;
+import static com.google.gerrit.reviewdb.client.Patch.MERGE_LIST;
+import static java.nio.charset.StandardCharsets.UTF_8;
+import static org.eclipse.jgit.lib.Constants.HEAD;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
+import com.google.gerrit.acceptance.AbstractDaemonTest;
+import com.google.gerrit.acceptance.NoHttpd;
+import com.google.gerrit.acceptance.PushOneCommit;
+import com.google.gerrit.common.RawInputUtil;
+import com.google.gerrit.extensions.api.changes.RevisionApi;
+import com.google.gerrit.extensions.common.CommitInfo;
+import com.google.gerrit.extensions.common.DiffInfo;
+import com.google.gerrit.extensions.restapi.BinaryResult;
+import com.google.gerrit.server.edit.ChangeEditModifier;
+import com.google.gerrit.server.edit.ChangeEditUtil;
+import com.google.gerrit.server.project.InvalidChangeOperationException;
+import com.google.gerrit.server.query.change.ChangeData;
+import com.google.inject.Inject;
+
+import org.eclipse.jgit.dircache.InvalidPathException;
+import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.revwalk.RevCommit;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.ByteArrayOutputStream;
+import java.util.List;
+import java.util.Set;
+
+@NoHttpd
+public class MergeListIT extends AbstractDaemonTest {
+
+  private String changeId;
+  private RevCommit merge;
+  private RevCommit parent1;
+  private RevCommit grandParent1;
+  private RevCommit parent2;
+  private RevCommit grandParent2;
+
+  @Inject
+  private ChangeEditModifier modifier;
+
+  @Inject
+  private ChangeEditUtil editUtil;
+
+  @Before
+  public void setup() throws Exception {
+    ObjectId initial = repo().exactRef(HEAD).getLeaf().getObjectId();
+
+    PushOneCommit.Result gp1 = pushFactory
+        .create(db, admin.getIdent(), testRepo, "grand parent 1",
+            ImmutableMap.of("foo", "foo-1.1", "bar", "bar-1.1"))
+        .to("refs/for/master");
+    grandParent1 = gp1.getCommit();
+
+    PushOneCommit.Result p1 = pushFactory
+        .create(db, admin.getIdent(), testRepo, "parent 1",
+            ImmutableMap.of("foo", "foo-1.2", "bar", "bar-1.2"))
+        .to("refs/for/master");
+    parent1 = p1.getCommit();
+
+    // reset HEAD in order to create a sibling of the first change
+    testRepo.reset(initial);
+
+    PushOneCommit.Result gp2 = pushFactory
+        .create(db, admin.getIdent(), testRepo, "grand parent 2",
+            ImmutableMap.of("foo", "foo-2.1", "bar", "bar-2.1"))
+        .to("refs/for/master");
+    grandParent2 = gp2.getCommit();
+
+    PushOneCommit.Result p2 = pushFactory
+        .create(db, admin.getIdent(), testRepo, "parent 2",
+            ImmutableMap.of("foo", "foo-2.2", "bar", "bar-2.2"))
+        .to("refs/for/master");
+    parent2 = p2.getCommit();
+
+    PushOneCommit m = pushFactory.create(db, admin.getIdent(), testRepo,
+        "merge", ImmutableMap.of("foo", "foo-1", "bar", "bar-2"));
+    m.setParents(ImmutableList.of(p1.getCommit(), p2.getCommit()));
+    PushOneCommit.Result result = m.to("refs/for/master");
+    result.assertOkStatus();
+    merge = result.getCommit();
+    changeId = result.getChangeId();
+  }
+
+  @Test
+  public void getMergeList() throws Exception {
+    List<CommitInfo> mergeList = current(changeId).getMergeList().get();
+    assertThat(mergeList).hasSize(2);
+    assertThat(mergeList.get(0).commit).isEqualTo(parent2.name());
+    assertThat(mergeList.get(1).commit).isEqualTo(grandParent2.name());
+
+    mergeList = current(changeId).getMergeList()
+        .withUninterestingParent(2).get();
+    assertThat(mergeList).hasSize(2);
+    assertThat(mergeList.get(0).commit).isEqualTo(parent1.name());
+    assertThat(mergeList.get(1).commit).isEqualTo(grandParent1.name());
+  }
+
+  @Test
+  public void getMergeListContent() throws Exception {
+    BinaryResult bin = current(changeId).file(MERGE_LIST).content();
+    ByteArrayOutputStream os = new ByteArrayOutputStream();
+    bin.writeTo(os);
+    String content = new String(os.toByteArray(), UTF_8);
+    assertThat(content).isEqualTo(
+        getMergeListContent(parent2, grandParent2));
+  }
+
+  @Test
+  public void getFileList() throws Exception {
+    assertThat(getFiles(changeId)).contains(MERGE_LIST);
+    assertThat(getFiles(changeId, 1)).contains(MERGE_LIST);
+    assertThat(getFiles(changeId, 2)).contains(MERGE_LIST);
+
+    assertThat(getFiles(createChange().getChangeId()))
+        .doesNotContain(MERGE_LIST);
+  }
+
+  @Test
+  public void getDiffForMergeList() throws Exception {
+    DiffInfo diff = getMergeListDiff(changeId);
+    assertDiffForNewFile(diff, merge, MERGE_LIST,
+        getMergeListContent(parent2, grandParent2));
+
+    diff = getMergeListDiff(changeId, 1);
+    assertDiffForNewFile(diff, merge, MERGE_LIST,
+        getMergeListContent(parent2, grandParent2));
+
+    diff = getMergeListDiff(changeId, 2);
+    assertDiffForNewFile(diff, merge, MERGE_LIST,
+        getMergeListContent(parent1, grandParent1));
+  }
+
+  @Test
+  public void editMergeList() throws Exception {
+    ChangeData cd = getOnlyElement(queryProvider.get().byKeyPrefix(changeId));
+    modifier.createEdit(cd.change(), cd.currentPatchSet());
+
+    exception.expect(InvalidPathException.class);
+    exception.expectMessage("Invalid path: " + MERGE_LIST);
+    modifier.modifyFile(editUtil.byChange(cd.change()).get(), MERGE_LIST,
+        RawInputUtil.create("new content"));
+  }
+
+  @Test
+  public void deleteMergeList() throws Exception {
+    ChangeData cd = getOnlyElement(queryProvider.get().byKeyPrefix(changeId));
+    modifier.createEdit(cd.change(), cd.currentPatchSet());
+
+    exception.expect(InvalidChangeOperationException.class);
+    exception.expectMessage("no changes were made");
+    modifier.deleteFile(editUtil.byChange(cd.change()).get(), MERGE_LIST);
+  }
+
+  private String getMergeListContent(RevCommit... commits) {
+    StringBuilder mergeList = new StringBuilder("Merge List:\n\n");
+    for (RevCommit c : commits) {
+      mergeList.append("* ")
+          .append(c.abbreviate(8).name())
+          .append(" ")
+          .append(c.getShortMessage())
+          .append("\n");
+    }
+    return mergeList.toString();
+  }
+
+  private Set<String> getFiles(String changeId) throws Exception {
+    return current(changeId).files().keySet();
+  }
+
+  private Set<String> getFiles(String changeId, int parent) throws Exception {
+    return current(changeId).files(parent).keySet();
+  }
+
+  private DiffInfo getMergeListDiff(String changeId) throws Exception {
+    return current(changeId).file(MERGE_LIST).diff();
+  }
+
+  private DiffInfo getMergeListDiff(String changeId, int parent)
+      throws Exception {
+    return current(changeId).file(MERGE_LIST).diff(parent);
+  }
+
+  private RevisionApi current(String changeId) throws Exception {
+    return gApi.changes()
+        .id(changeId)
+        .current();
+  }
+}

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/api/revision/RevisionIT.java

@@ -20,11 +20,13 @@ import static com.google.gerrit.acceptance.PushOneCommit.FILE_NAME;
 import static com.google.gerrit.acceptance.PushOneCommit.PATCH;
 import static com.google.gerrit.acceptance.PushOneCommit.SUBJECT;
 import static com.google.gerrit.reviewdb.client.Patch.COMMIT_MSG;
+import static com.google.gerrit.reviewdb.client.Patch.MERGE_LIST;
 import static com.google.gerrit.server.group.SystemGroupBackend.REGISTERED_USERS;
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static org.eclipse.jgit.lib.Constants.HEAD;
 import static org.junit.Assert.fail;
 
+import com.google.common.base.Joiner;
 import com.google.common.base.Predicate;
 import com.google.common.collect.Iterables;
 import com.google.gerrit.acceptance.AbstractDaemonTest;
@@ -45,7 +47,6 @@ import com.google.gerrit.extensions.client.ChangeStatus;
 import com.google.gerrit.extensions.client.SubmitType;
 import com.google.gerrit.extensions.common.ChangeInfo;
 import com.google.gerrit.extensions.common.ChangeMessageInfo;
-import com.google.gerrit.extensions.common.ChangeType;
 import com.google.gerrit.extensions.common.CommentInfo;
 import com.google.gerrit.extensions.common.DiffInfo;
 import com.google.gerrit.extensions.common.FileInfo;
@@ -539,7 +540,7 @@ public class RevisionIT extends AbstractDaemonTest {
         .revision(r.getCommit().name())
         .files()
         .keySet()
-      ).containsExactly(COMMIT_MSG, "foo", "bar");
+      ).containsExactly(COMMIT_MSG, MERGE_LIST, "foo", "bar");
 
     // list files against parent 1
     assertThat(gApi.changes()
@@ -547,7 +548,7 @@ public class RevisionIT extends AbstractDaemonTest {
         .revision(r.getCommit().name())
         .files(1)
         .keySet()
-      ).containsExactly(COMMIT_MSG, "bar");
+      ).containsExactly(COMMIT_MSG, MERGE_LIST, "bar");
 
     // list files against parent 2
     assertThat(gApi.changes()
@@ -555,7 +556,7 @@ public class RevisionIT extends AbstractDaemonTest {
         .revision(r.getCommit().name())
         .files(2)
         .keySet()
-      ).containsExactly(COMMIT_MSG, "foo");
+      ).containsExactly(COMMIT_MSG, MERGE_LIST, "foo");
   }
 
   @Test
@@ -853,66 +854,40 @@ public class RevisionIT extends AbstractDaemonTest {
         .file(path)
         .diff();
 
-    List<String> expectedLines = new ArrayList<>();
+    List<String> headers = new ArrayList<>();
     if (path.equals(COMMIT_MSG)) {
       RevCommit c = pushResult.getCommit();
 
       RevCommit parentCommit = c.getParents()[0];
       String parentCommitId = testRepo.getRevWalk().getObjectReader()
           .abbreviate(parentCommit.getId(), 8).name();
-      expectedLines.add("Parent:     " + parentCommitId + " ("
+      headers.add("Parent:     " + parentCommitId + " ("
           + parentCommit.getShortMessage() + ")");
 
       SimpleDateFormat dtfmt =
           new SimpleDateFormat("yyyy-MM-dd HH:mm:ss Z", Locale.US);
       PersonIdent author = c.getAuthorIdent();
       dtfmt.setTimeZone(author.getTimeZone());
-      expectedLines.add("Author:     " + author.getName() + " <"
+      headers.add("Author:     " + author.getName() + " <"
           + author.getEmailAddress() + ">");
-      expectedLines.add("AuthorDate: "
+      headers.add("AuthorDate: "
           + dtfmt.format(Long.valueOf(author.getWhen().getTime())));
 
       PersonIdent committer = c.getCommitterIdent();
       dtfmt.setTimeZone(committer.getTimeZone());
-      expectedLines.add("Commit:     " + committer.getName() + " <"
+      headers.add("Commit:     " + committer.getName() + " <"
           + committer.getEmailAddress() + ">");
-      expectedLines.add("CommitDate: "
+      headers.add("CommitDate: "
           + dtfmt.format(Long.valueOf(committer.getWhen().getTime())));
-      expectedLines.add("");
+      headers.add("");
     }
 
-    for (String line : expectedContentSideB.split("\n")) {
+    if (!headers.isEmpty()) {
-      expectedLines.add(line);
+      String header = Joiner.on("\n").join(headers);
+      expectedContentSideB = header + "\n" + expectedContentSideB;
     }
 
-    assertThat(diff.binary).isNull();
+    assertDiffForNewFile(diff, pushResult.getCommit(), path,
-    assertThat(diff.changeType).isEqualTo(ChangeType.ADDED);
+        expectedContentSideB);
-    assertThat(diff.diffHeader).isNotNull();
-    assertThat(diff.intralineStatus).isNull();
-    assertThat(diff.webLinks).isNull();
-
-    assertThat(diff.metaA).isNull();
-    assertThat(diff.metaB).isNotNull();
-    assertThat(diff.metaB.commitId).isEqualTo(pushResult.getCommit().name());
-    assertThat(diff.metaB.contentType).isEqualTo(
-        path.equals(COMMIT_MSG)
-            ? "text/x-gerrit-commit-message"
-            : "text/plain");
-    assertThat(diff.metaB.lines).isEqualTo(expectedLines.size());
-    assertThat(diff.metaB.name).isEqualTo(path);
-    assertThat(diff.metaB.webLinks).isNull();
-
-    assertThat(diff.content).hasSize(1);
-    DiffInfo.ContentEntry contentEntry = diff.content.get(0);
-    assertThat(contentEntry.b).hasSize(expectedLines.size());
-    for (int i = 0; i < contentEntry.b.size(); i++) {
-      assertThat(contentEntry.b.get(i)).isEqualTo(expectedLines.get(i));
-    }
-    assertThat(contentEntry.a).isNull();
-    assertThat(contentEntry.ab).isNull();
-    assertThat(contentEntry.common).isNull();
-    assertThat(contentEntry.editA).isNull();
-    assertThat(contentEntry.editB).isNull();
-    assertThat(contentEntry.skip).isNull();
   }
 }

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/server/change/CommentsIT.java

@@ -32,9 +32,11 @@ import com.google.gerrit.extensions.api.changes.ReviewInput.DraftHandling;
 import com.google.gerrit.extensions.client.Comment;
 import com.google.gerrit.extensions.client.Side;
 import com.google.gerrit.extensions.common.CommentInfo;
+import com.google.gerrit.extensions.restapi.BadRequestException;
 import com.google.gerrit.extensions.restapi.IdString;
 import com.google.gerrit.extensions.restapi.ResourceNotFoundException;
 import com.google.gerrit.extensions.restapi.TopLevelResource;
+import com.google.gerrit.reviewdb.client.Patch;
 import com.google.gerrit.server.change.ChangeResource;
 import com.google.gerrit.server.change.ChangesCollection;
 import com.google.gerrit.server.change.PostReview;
@@ -148,8 +150,8 @@ public class CommentsIT extends AbstractDaemonTest {
   @Test
   public void postCommentOnMergeCommitChange() throws Exception {
     for (Integer line : lines) {
-      final String file = "/COMMIT_MSG";
+      String file = "foo";
-      PushOneCommit.Result r = createMergeCommitChange("refs/for/master");
+      PushOneCommit.Result r = createMergeCommitChange("refs/for/master", file);
       String changeId = r.getChangeId();
       String revId = r.getCommit().getName();
       ReviewInput input = new ReviewInput();
@@ -165,6 +167,39 @@ public class CommentsIT extends AbstractDaemonTest {
       assertThat(Lists.transform(result.get(file), infoToInput(file)))
           .containsExactly(c1, c2, c3, c4);
     }
+
+    // for the commit message comments on the auto-merge are not possible
+    for (Integer line : lines) {
+      String file = Patch.COMMIT_MSG;
+      PushOneCommit.Result r = createMergeCommitChange("refs/for/master");
+      String changeId = r.getChangeId();
+      String revId = r.getCommit().getName();
+      ReviewInput input = new ReviewInput();
+      CommentInput c1 = newComment(file, Side.REVISION, line, "ps-1");
+      CommentInput c2 = newCommentOnParent(file, 1, line, "parent-1 of ps-1");
+      CommentInput c3 = newCommentOnParent(file, 2, line, "parent-2 of ps-1");
+      input.comments = new HashMap<>();
+      input.comments.put(file, ImmutableList.of(c1, c2, c3));
+      revision(r).review(input);
+      Map<String, List<CommentInfo>> result = getPublishedComments(changeId, revId);
+      assertThat(result).isNotEmpty();
+      assertThat(Lists.transform(result.get(file), infoToInput(file)))
+          .containsExactly(c1, c2, c3);
+    }
+  }
+
+  @Test
+  public void postCommentOnCommitMessageOnAutoMerge() throws Exception {
+    PushOneCommit.Result r = createMergeCommitChange("refs/for/master");
+    ReviewInput input = new ReviewInput();
+    CommentInput c =
+        newComment(Patch.COMMIT_MSG, Side.PARENT, 0, "comment on auto-merge");
+    input.comments = new HashMap<>();
+    input.comments.put(Patch.COMMIT_MSG, ImmutableList.of(c));
+    exception.expect(BadRequestException.class);
+    exception.expectMessage(
+        "cannot comment on " + Patch.COMMIT_MSG + " on auto-merge");
+    revision(r).review(input);
   }
 
   @Test

gerrit-gwtui-common/src/main/java/com/google/gerrit/client/info/FileInfo.java

@@ -56,6 +56,12 @@ public class FileInfo extends JavaScriptObject {
         } else if (Patch.COMMIT_MSG.equals(b.path())) {
           return 1;
         }
+        if (Patch.MERGE_LIST.equals(a.path())) {
+          return -1;
+        } else if (Patch.MERGE_LIST.equals(b.path())) {
+          return 1;
+        }
+
         // Look at file suffixes to check if it makes sense to use a different order
         int s1 = a.path().lastIndexOf('.');
         int s2 = b.path().lastIndexOf('.');
@@ -76,9 +82,15 @@ public class FileInfo extends JavaScriptObject {
   }
 
   public static String getFileName(String path) {
-    String fileName = Patch.COMMIT_MSG.equals(path)
+    String fileName;
-        ? "Commit Message"
+    if (Patch.COMMIT_MSG.equals(path)) {
-        : path;
+      fileName = "Commit Message";
+    } else if (Patch.MERGE_LIST.equals(path)) {
+      fileName = "Merge List";
+    } else {
+      fileName = path;
+    }
+
     int s = fileName.lastIndexOf('/');
     return s >= 0 ? fileName.substring(s + 1) : fileName;
   }

gerrit-gwtui/src/main/java/com/google/gerrit/client/Dispatcher.java

@@ -486,7 +486,11 @@ public class Dispatcher {
     } else if ("unified".equals(panel)) {
       unified(token, baseId, id, side, line);
     } else if ("edit".equals(panel)) {
-      codemirrorForEdit(token, id, line);
+      if (!Patch.isMagic(id.get()) || Patch.COMMIT_MSG.equals(id.get())) {
+        codemirrorForEdit(token, id, line);
+      } else {
+        Gerrit.display(token, new NotFoundScreen());
+      }
     } else {
       Gerrit.display(token, new NotFoundScreen());
     }

gerrit-gwtui/src/main/java/com/google/gerrit/client/change/FileTable.java

@@ -267,11 +267,18 @@ public class FileTable extends FlowPanel {
     if (table != null) {
       String self = Gerrit.selfRedirect(null);
       for (FileInfo info : Natives.asList(table.list)) {
-        Window.open(self + "#" + url(info), "_blank", null);
+        if (canOpen(info.path())) {
+          Window.open(self + "#" + url(info), "_blank", null);
+        }
       }
     }
   }
 
+  private boolean canOpen(String path) {
+    return mode != Mode.EDIT || !Patch.isMagic(path)
+        || Patch.COMMIT_MSG.equals(path);
+  }
+
   private void setTable(MyTable table) {
     clear();
     add(table);
@@ -429,7 +436,10 @@ public class FileTable extends FlowPanel {
     @Override
     protected void onOpenRow(int row) {
       if (1 <= row && row <= list.length()) {
-        Gerrit.display(url(list.get(row - 1)));
+        FileInfo info = list.get(row - 1);
+        if (canOpen(info.path())) {
+          Gerrit.display(url(info));
+        }
       }
     }
 
@@ -452,7 +462,10 @@ public class FileTable extends FlowPanel {
 
       @Override
       public void onKeyPress(KeyPressEvent event) {
-        Gerrit.display(url(list.get(index)));
+        FileInfo info = list.get(index);
+        if (canOpen(info.path())) {
+          Gerrit.display(url(info));
+        }
       }
     }
   }
@@ -538,7 +551,7 @@ public class FileTable extends FlowPanel {
       bytesDeleted = 0;
       for (int i = 0; i < list.length(); i++) {
         FileInfo info = list.get(i);
-        if (!Patch.COMMIT_MSG.equals(info.path())) {
+        if (!Patch.isMagic(info.path())) {
           if (!info.binary()) {
             hasNonBinaryFile = true;
             inserted += info.linesInserted();
@@ -628,7 +641,7 @@ public class FileTable extends FlowPanel {
     private void columnDeleteRestore(SafeHtmlBuilder sb, FileInfo info) {
       sb.openTd().setStyleName(R.css().restoreDelete());
       if (hasUser) {
-        if (!Patch.COMMIT_MSG.equals(info.path())) {
+        if (!Patch.isMagic(info.path())) {
           boolean editable = isEditable(info);
           sb.openDiv()
             .openElement("button")
@@ -659,7 +672,7 @@ public class FileTable extends FlowPanel {
 
     private void columnStatus(SafeHtmlBuilder sb, FileInfo info) {
       sb.openTd().setStyleName(R.css().status());
-      if (!Patch.COMMIT_MSG.equals(info.path())
+      if (!Patch.isMagic(info.path())
           && info.status() != null
           && !ChangeType.MODIFIED.matches(info.status())) {
         sb.append(info.status());
@@ -668,20 +681,43 @@ public class FileTable extends FlowPanel {
     }
 
     private void columnPath(SafeHtmlBuilder sb, FileInfo info) {
-      sb.openTd()
-        .setStyleName(R.css().pathColumn())
-        .openAnchor();
-
       String path = info.path();
+
+      sb.openTd()
+        .setStyleName(R.css().pathColumn());
+
+      if (!canOpen(path)) {
+        sb.openDiv();
+        appendPath(path);
+        sb.closeDiv();
+        sb.closeTd();
+        return;
+      }
+
+      sb.openAnchor();
+
       if (mode == Mode.EDIT && !isEditable(info)) {
         sb.setAttribute("onclick", RESTORE + "(event," + info._row() + ")");
       } else {
         sb.setAttribute("href", "#" + url(info))
           .setAttribute("onclick", OPEN + "(event," + info._row() + ")");
       }
+      appendPath(path);
+      sb.closeAnchor();
+      if (info.oldPath() != null) {
+        sb.br();
+        sb.openSpan().setStyleName(R.css().renameCopySource())
+          .append(info.oldPath())
+          .closeSpan();
+      }
+      sb.closeTd();
+    }
 
+    private void appendPath(String path) {
       if (Patch.COMMIT_MSG.equals(path)) {
         sb.append(Util.C.commitMessage());
+      } else if (Patch.MERGE_LIST.equals(path)) {
+        sb.append(Util.C.mergeList());
       } else if (Gerrit.getUserPreferences().muteCommonPathPrefixes()) {
         int commonPrefixLen = commonPrefix(path);
         if (commonPrefixLen > 0) {
@@ -694,15 +730,6 @@ public class FileTable extends FlowPanel {
       } else {
         sb.append(path);
       }
-
-      sb.closeAnchor();
-      if (info.oldPath() != null) {
-        sb.br();
-        sb.openSpan().setStyleName(R.css().renameCopySource())
-          .append(info.oldPath())
-          .closeSpan();
-      }
-      sb.closeTd();
     }
 
     private int commonPrefix(String path) {
@@ -784,7 +811,7 @@ public class FileTable extends FlowPanel {
 
     private void columnDelta1(SafeHtmlBuilder sb, FileInfo info) {
       sb.openTd().setStyleName(R.css().deltaColumn1());
-      if (!Patch.COMMIT_MSG.equals(info.path()) && !info.binary()) {
+      if (!Patch.isMagic(info.path()) && !info.binary()) {
         if (showChangeSizeBars) {
           sb.append(info.linesInserted() + info.linesDeleted());
         } else if (!ChangeType.DELETED.matches(info.status())) {
@@ -813,7 +840,7 @@ public class FileTable extends FlowPanel {
     private void columnDelta2(SafeHtmlBuilder sb, FileInfo info) {
       sb.openTd().setStyleName(R.css().deltaColumn2());
       if (showChangeSizeBars
-          && !Patch.COMMIT_MSG.equals(info.path()) && !info.binary()
+          && !Patch.isMagic(info.path()) && !info.binary()
           && (info.linesInserted() != 0 || info.linesDeleted() != 0)) {
         int w = 80;
         int t = inserted + deleted;

gerrit-gwtui/src/main/java/com/google/gerrit/client/change/Message.java

@@ -176,6 +176,10 @@ class Message extends Composite {
     if (l != null) {
       comments.add(new FileComments(clp, ps, Util.C.commitMessage(), l));
     }
+    l = m.remove(Patch.MERGE_LIST);
+    if (l != null) {
+      comments.add(new FileComments(clp, ps, Util.C.mergeList(), l));
+    }
     for (Map.Entry<String, List<CommentInfo>> e : m.entrySet()) {
       comments.add(new FileComments(clp, ps, e.getKey(), e.getValue()));
     }

gerrit-gwtui/src/main/java/com/google/gerrit/client/change/ReplyBox.java

@@ -422,12 +422,17 @@ public class ReplyBox extends Composite {
       comments.add(new FileComments(clp, psId,
           Util.C.commitMessage(), copyPath(Patch.COMMIT_MSG, l)));
     }
+    l = m.get(Patch.MERGE_LIST);
+    if (l != null) {
+      comments.add(new FileComments(clp, psId, Util.C.commitMessage(),
+          copyPath(Patch.MERGE_LIST, l)));
+    }
 
     List<String> paths = new ArrayList<>(m.keySet());
     Collections.sort(paths);
 
     for (String path : paths) {
-      if (!path.equals(Patch.COMMIT_MSG)) {
+      if (!Patch.isMagic(path)) {
         comments.add(new FileComments(clp, psId,
             path, copyPath(path, m.get(path))));
       }

gerrit-gwtui/src/main/java/com/google/gerrit/client/changes/ChangeConstants.java

@@ -63,6 +63,7 @@ public interface ChangeConstants extends Constants {
   String patchTableColumnComments();
   String patchTableColumnSize();
   String commitMessage();
+  String mergeList();
 
   String patchTablePrev();
   String patchTableNext();

gerrit-gwtui/src/main/java/com/google/gerrit/client/changes/ChangeConstants.properties

@@ -45,6 +45,7 @@ patchTableColumnName = File Path
 patchTableColumnComments = Comments
 patchTableColumnSize = Size
 commitMessage = Commit Message
+mergeList = Merge List
 
 patchTablePrev = Previous file
 patchTableNext = Next file

gerrit-gwtui/src/main/java/com/google/gerrit/client/diff/Header.java

@@ -122,6 +122,8 @@ public class Header extends Composite {
     SafeHtmlBuilder b = new SafeHtmlBuilder();
     if (Patch.COMMIT_MSG.equals(path)) {
       return b.append(Util.C.commitMessage());
+    } else if (Patch.MERGE_LIST.equals(path)) {
+      return b.append(Util.C.mergeList());
     }
 
     int s = path.lastIndexOf('/') + 1;

gerrit-gwtui/src/main/java/com/google/gerrit/client/diff/PatchSetSelectBox.java

@@ -128,7 +128,7 @@ class PatchSetSelectBox extends Composite {
     if (meta == null) {
       return;
     }
-    if (!Patch.COMMIT_MSG.equals(path)) {
+    if (!Patch.isMagic(path)) {
       linkPanel.add(createDownloadLink());
     }
     if (!binary && open && idActive != null && Gerrit.isSignedIn()) {
@@ -147,7 +147,7 @@ class PatchSetSelectBox extends Composite {
 
   void setUpBlame(final CodeMirror cm, final boolean isBase,
       final PatchSet.Id rev, final String path) {
-    if (!Patch.COMMIT_MSG.equals(path) && Gerrit.isSignedIn()
+    if (!Patch.isMagic(path) && Gerrit.isSignedIn()
         && Gerrit.info().change().allowBlame()) {
       Anchor blameIcon = createBlameIcon();
       blameIcon.addClickHandler(new ClickHandler() {

gerrit-reviewdb/src/main/java/com/google/gerrit/reviewdb/client/Patch.java

@@ -22,6 +22,22 @@ public final class Patch {
   /** Magical file name which represents the commit message. */
   public static final String COMMIT_MSG = "/COMMIT_MSG";
 
+  /** Magical file name which represents the merge list of a merge commit. */
+  public static final String MERGE_LIST = "/MERGE_LIST";
+
+  /**
+   * Checks if the given path represents a magic file. A magic file is a
+   * generated file that is automatically included into changes. It does not
+   * exist in the commit of the patch set.
+   *
+   * @param path the file path
+   * @return {@code true} if the path represents a magic file, otherwise
+   *         {@code false}.
+   */
+  public static boolean isMagic(String path) {
+    return COMMIT_MSG.equals(path) || MERGE_LIST.equals(path);
+  }
+
   public static class Key extends StringKey<PatchSet.Id> {
     private static final long serialVersionUID = 1L;
 

gerrit-server/src/main/java/com/google/gerrit/server/PatchLineCommentsUtil.java

@@ -14,6 +14,8 @@
 
 package com.google.gerrit.server;
 
+import static java.util.stream.Collectors.toList;
+
 import static com.google.common.base.MoreObjects.firstNonNull;
 import static com.google.common.base.Preconditions.checkArgument;
 import static java.util.stream.Collectors.toList;
@@ -27,6 +29,7 @@ import com.google.gerrit.extensions.client.Side;
 import com.google.gerrit.extensions.common.CommentInfo;
 import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.reviewdb.client.Change;
+import com.google.gerrit.reviewdb.client.Patch;
 import com.google.gerrit.reviewdb.client.PatchLineComment;
 import com.google.gerrit.reviewdb.client.PatchLineComment.Status;
 import com.google.gerrit.reviewdb.client.PatchSet;
@@ -210,10 +213,27 @@ public class PatchLineCommentsUtil {
   public List<PatchLineComment> publishedByPatchSet(ReviewDb db,
       ChangeNotes notes, PatchSet.Id psId) throws OrmException {
     if (!migration.readChanges()) {
-      return sort(
+      return removeCommentsOnAncestorOfCommitMessage(sort(
-          db.patchComments().publishedByPatchSet(psId).toList());
+          db.patchComments().publishedByPatchSet(psId).toList()));
     }
-    return commentsOnPatchSet(notes.load().getComments().values(), psId);
+    return removeCommentsOnAncestorOfCommitMessage(
+        commentsOnPatchSet(notes.load().getComments().values(), psId));
+  }
+
+  /**
+   * For the commit message the A side in a diff view is always empty when a
+   * comparison against an ancestor is done, so there can't be any comments on
+   * this ancestor. However earlier we showed the auto-merge commit message on
+   * side A when for a merge commit a comparison against the auto-merge was
+   * done. From that time there may still be comments on the auto-merge commit
+   * message and those we want to filter out.
+   */
+  private List<PatchLineComment> removeCommentsOnAncestorOfCommitMessage(
+      List<PatchLineComment> list) {
+    return list.stream()
+        .filter(c -> c.getSide() != 0
+            || !Patch.COMMIT_MSG.equals(c.getKey().getParentKey().get()))
+        .collect(toList());
   }
 
   public List<PatchLineComment> draftByPatchSetAuthor(ReviewDb db,

gerrit-server/src/main/java/com/google/gerrit/server/change/ChangeJson.java

@@ -1056,6 +1056,7 @@ public class ChangeJson {
     if (has(ALL_FILES) || (out.isCurrent && has(CURRENT_FILES))) {
       out.files = fileInfoJson.toFileInfoMap(c, in);
       out.files.remove(Patch.COMMIT_MSG);
+      out.files.remove(Patch.MERGE_LIST);
     }
 
     if ((out.isCurrent || (out.draft != null && out.draft))

gerrit-server/src/main/java/com/google/gerrit/server/change/FileContentUtil.java

@@ -54,6 +54,7 @@ import java.util.zip.ZipOutputStream;
 @Singleton
 public class FileContentUtil {
   public static final String TEXT_X_GERRIT_COMMIT_MESSAGE = "text/x-gerrit-commit-message";
+  public static final String TEXT_X_GERRIT_MERGE_LIST = "text/x-gerrit-merge-list";
   private static final String X_GIT_SYMLINK = "x-git/symlink";
   private static final String X_GIT_GITLINK = "x-git/gitlink";
   private static final int MAX_SIZE = 5 << 20;
@@ -264,6 +265,9 @@ public class FileContentUtil {
         if (Patch.COMMIT_MSG.equals(path)) {
           return TEXT_X_GERRIT_COMMIT_MESSAGE;
         }
+        if (Patch.MERGE_LIST.equals(path)) {
+          return TEXT_X_GERRIT_MERGE_LIST;
+        }
         if (project != null) {
           for (ProjectState p : project.tree()) {
             String t = p.getConfig().getMimeTypes().getMimeType(path);

gerrit-server/src/main/java/com/google/gerrit/server/change/GetContent.java

@@ -24,6 +24,8 @@ import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.PatchSetUtil;
 import com.google.gerrit.server.git.GitRepositoryManager;
 import com.google.gerrit.server.notedb.ChangeNotes;
+import com.google.gerrit.server.patch.ComparisonType;
+import com.google.gerrit.server.patch.Text;
 import com.google.gerrit.server.project.NoSuchChangeException;
 import com.google.gwtorm.server.OrmException;
 import com.google.inject.Inject;
@@ -68,6 +70,12 @@ public class GetContent implements RestReadView<FileResource> {
       return BinaryResult.create(msg)
           .setContentType(FileContentUtil.TEXT_X_GERRIT_COMMIT_MESSAGE)
           .base64();
+    } else if (Patch.MERGE_LIST.equals(path)) {
+      byte[] mergeList = getMergeList(
+          rsrc.getRevision().getChangeResource().getNotes());
+      return BinaryResult.create(mergeList)
+          .setContentType(FileContentUtil.TEXT_X_GERRIT_MERGE_LIST)
+          .base64();
     }
     return fileContentUtil.getContent(
         rsrc.getRevision().getControl().getProjectControl().getProjectState(),
@@ -92,4 +100,22 @@ public class GetContent implements RestReadView<FileResource> {
       throw new NoSuchChangeException(changeId, e);
     }
   }
+
+  private byte[] getMergeList(ChangeNotes notes)
+      throws NoSuchChangeException, OrmException, IOException {
+    Change.Id changeId = notes.getChangeId();
+    PatchSet ps = psUtil.current(db.get(), notes);
+    if (ps == null) {
+      throw new NoSuchChangeException(changeId);
+    }
+
+    try (Repository git = gitManager.openRepository(notes.getProjectName());
+        RevWalk revWalk = new RevWalk(git)) {
+      return Text.forMergeList(ComparisonType.againstAutoMerge(),
+          revWalk.getObjectReader(),
+          ObjectId.fromString(ps.getRevision().get())).getContent();
+    } catch (RepositoryNotFoundException e) {
+      throw new NoSuchChangeException(changeId, e);
+    }
+  }
 }

gerrit-server/src/main/java/com/google/gerrit/server/change/GetMergeList.java

@@ -22,6 +22,7 @@ import com.google.gerrit.extensions.restapi.Response;
 import com.google.gerrit.extensions.restapi.RestReadView;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.server.git.GitRepositoryManager;
+import com.google.gerrit.server.patch.MergeListBuilder;
 import com.google.inject.Inject;
 
 import org.eclipse.jgit.lib.ObjectId;
@@ -46,7 +47,8 @@ public class GetMergeList implements RestReadView<RevisionResource> {
   private boolean addLinks;
 
   @Inject
-  GetMergeList(GitRepositoryManager repoManager, ChangeJson.Factory json) {
+  GetMergeList(GitRepositoryManager repoManager,
+      ChangeJson.Factory json) {
     this.repoManager = repoManager;
     this.json = json;
   }
@@ -62,7 +64,6 @@ public class GetMergeList implements RestReadView<RevisionResource> {
   @Override
   public Response<List<CommitInfo>> apply(RevisionResource rsrc)
       throws BadRequestException, IOException {
-    List<CommitInfo> result = new ArrayList<>();
     Project.NameKey p = rsrc.getChange().getProject();
     try (Repository repo = repoManager.openRepository(p);
         RevWalk rw = new RevWalk(repo)) {
@@ -76,26 +77,22 @@ public class GetMergeList implements RestReadView<RevisionResource> {
       }
 
       if (commit.getParentCount() < 2) {
-        return Response.<List<CommitInfo>> ok(ImmutableList.<CommitInfo> of());
+        return createResponse(rsrc, ImmutableList.<CommitInfo> of());
-      }
-
-      for (int parent = 0; parent < commit.getParentCount(); parent++) {
-        if (parent == uninterestingParent - 1) {
-          rw.markUninteresting(commit.getParent(parent));
-        } else {
-          rw.markStart(commit.getParent(parent));
-        }
       }
 
+      List<RevCommit> commits =
+          MergeListBuilder.build(rw, commit, uninterestingParent);
+      List<CommitInfo> result = new ArrayList<>(commits.size());
       ChangeJson changeJson = json.create(ChangeJson.NO_OPTIONS);
-      RevCommit c;
+      for (RevCommit c : commits) {
-      while ((c = rw.next()) != null) {
+        result.add(changeJson.toCommit(rsrc.getControl(), rw, c, addLinks, true));
-        CommitInfo info =
-            changeJson.toCommit(rsrc.getControl(), rw, c, addLinks, true);
-        result.add(info);
       }
+      return createResponse(rsrc, result);
     }
+  }
 
+  private static Response<List<CommitInfo>> createResponse(
+      RevisionResource rsrc, List<CommitInfo> result) {
     Response<List<CommitInfo>> r = Response.ok(result);
     if (rsrc.isCacheable()) {
       r.caching(CacheControl.PRIVATE(7, TimeUnit.DAYS));

gerrit-server/src/main/java/com/google/gerrit/server/change/PostReview.java

@@ -324,11 +324,19 @@ public class PostReview implements RestModifyView<RevisionResource, ReviewInput>
     while (mapItr.hasNext()) {
       Map.Entry<String, List<CommentInput>> ent = mapItr.next();
       String path = ent.getKey();
-      if (!filePaths.contains(path) && !Patch.COMMIT_MSG.equals(path)) {
+      if (!filePaths.contains(path) && !Patch.isMagic(path)) {
         throw new BadRequestException(String.format(
             "file %s not found in revision %s",
             path, revision.getChange().currentPatchSetId()));
       }
+      if (Patch.isMagic(path)) {
+        for (CommentInput comment : ent.getValue()) {
+          if (comment.side == Side.PARENT && comment.parent == null) {
+            throw new BadRequestException(
+                String.format("cannot comment on %s on auto-merge", path));
+          }
+        }
+      }
 
       List<CommentInput> list = ent.getValue();
       if (list == null) {

gerrit-server/src/main/java/com/google/gerrit/server/events/EventFactory.java

@@ -496,7 +496,7 @@ public class EventFactory {
       List<Patch> list =
           patchListCache.get(change, patchSet).toPatchList(pId);
       for (Patch pe : list) {
-        if (!Patch.COMMIT_MSG.equals(pe.getFileName())) {
+        if (!Patch.isMagic(pe.getFileName())) {
           p.sizeDeletions -= pe.getDeletions();
           p.sizeInsertions += pe.getInsertions();
         }

gerrit-server/src/main/java/com/google/gerrit/server/mail/ChangeEmail.java

@@ -259,7 +259,7 @@ public abstract class ChangeEmail extends NotificationEmail {
         detail.append("---\n");
         PatchList patchList = getPatchList();
         for (PatchListEntry p : patchList.getPatches()) {
-          if (Patch.COMMIT_MSG.equals(p.getNewName())) {
+          if (Patch.isMagic(p.getNewName())) {
             continue;
           }
           detail.append(p.getChangeType().getCode())

gerrit-server/src/main/java/com/google/gerrit/server/mail/CommentSender.java

@@ -75,7 +75,7 @@ public class CommentSender extends ReplyToChangeSender {
     Set<String> paths = new HashSet<>();
     for (PatchLineComment c : plc) {
       Patch.Key p = c.getKey().getParentKey();
-      if (!Patch.COMMIT_MSG.equals(p.getFileName())) {
+      if (!Patch.isMagic(p.getFileName())) {
         paths.add(p.getFileName());
       }
     }
@@ -137,6 +137,8 @@ public class CommentSender extends ReplyToChangeSender {
           }
           if (Patch.COMMIT_MSG.equals(pk.get())) {
             cmts.append("Commit Message:\n\n");
+          } else if (Patch.MERGE_LIST.equals(pk.get())) {
+            cmts.append("Merge List:\n\n");
           } else {
             cmts.append("File ").append(pk.get()).append(":\n\n");
           }
@@ -144,8 +146,7 @@ public class CommentSender extends ReplyToChangeSender {
 
           if (patchList != null) {
             try {
-              currentFileData =
+              currentFileData = new PatchFile(repo, patchList, pk.get());
-                  new PatchFile(repo, patchList, pk.get());
             } catch (IOException e) {
               log.warn(String.format(
                   "Cannot load %s from %s in %s",

gerrit-server/src/main/java/com/google/gerrit/server/patch/ComparisonType.java

@@ -0,0 +1,77 @@
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.server.patch;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.gerrit.server.ioutil.BasicSerialization.readVarInt32;
+import static com.google.gerrit.server.ioutil.BasicSerialization.writeVarInt32;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+public class ComparisonType {
+
+  /** 1-based parent */
+  private final Integer parentNum;
+
+  private final boolean autoMerge;
+
+  public static ComparisonType againstOtherPatchSet() {
+    return new ComparisonType(null, false);
+  }
+
+  public static ComparisonType againstParent(int parentNum) {
+    return new ComparisonType(parentNum, false);
+  }
+
+  public static ComparisonType againstAutoMerge() {
+    return new ComparisonType(null, true);
+  }
+
+  private ComparisonType(Integer parentNum, boolean autoMerge) {
+    this.parentNum = parentNum;
+    this.autoMerge = autoMerge;
+  }
+
+  public boolean isAgainstParentOrAutoMerge() {
+    return isAgainstParent() || isAgainstAutoMerge();
+  }
+
+  public boolean isAgainstParent() {
+    return parentNum != null;
+  }
+
+  public boolean isAgainstAutoMerge() {
+    return autoMerge;
+  }
+
+  public int getParentNum() {
+    checkNotNull(parentNum);
+    return parentNum;
+  }
+
+  void writeTo(OutputStream out) throws IOException {
+    writeVarInt32(out, parentNum != null ? parentNum : 0);
+    writeVarInt32(out, autoMerge ? 1 : 0);
+  }
+
+  static ComparisonType readFrom(InputStream in) throws IOException {
+    int p = readVarInt32(in);
+    Integer parentNum = p > 0 ? p : null;
+    boolean autoMerge = readVarInt32(in) != 0;
+    return new ComparisonType(parentNum, autoMerge);
+  }
+}

gerrit-server/src/main/java/com/google/gerrit/server/patch/MergeListBuilder.java

@@ -0,0 +1,52 @@
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.server.patch;
+
+import com.google.common.collect.ImmutableList;
+
+import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+
+public class MergeListBuilder {
+  public static List<RevCommit> build(RevWalk rw, RevCommit merge,
+      int uninterestingParent) throws IOException {
+    rw.reset();
+    rw.parseBody(merge);
+    if (merge.getParentCount() < 2) {
+      return ImmutableList.of();
+    }
+
+    for (int parent = 0; parent < merge.getParentCount(); parent++) {
+      RevCommit parentCommit = merge.getParent(parent);
+      rw.parseBody(parentCommit);
+      if (parent == uninterestingParent - 1) {
+        rw.markUninteresting(parentCommit);
+      } else {
+        rw.markStart(parentCommit);
+      }
+    }
+
+    List<RevCommit> result = new ArrayList<>();
+    RevCommit c;
+    while ((c = rw.next()) != null) {
+      result.add(c);
+    }
+    return result;
+  }
+}

gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchFile.java

@@ -44,9 +44,8 @@ public class PatchFile {
   private Text a;
   private Text b;
 
-  public PatchFile(final Repository repo, final PatchList patchList,
+  public PatchFile(Repository repo, PatchList patchList, String fileName)
-      final String fileName) throws MissingObjectException,
+      throws MissingObjectException, IncorrectObjectTypeException, IOException {
-      IncorrectObjectTypeException, IOException {
     this.repo = repo;
     this.entry = patchList.get(fileName);
 
@@ -55,7 +54,7 @@ public class PatchFile {
       final RevCommit bCommit = rw.parseCommit(patchList.getNewId());
 
       if (Patch.COMMIT_MSG.equals(fileName)) {
-        if (patchList.isAgainstParent()) {
+        if (patchList.getComparisonType().isAgainstParentOrAutoMerge()) {
           a = Text.EMPTY;
         } else {
           // For the initial commit, we have an empty tree on Side A
@@ -68,7 +67,16 @@ public class PatchFile {
 
         aTree = null;
         bTree = null;
+      } else if (Patch.MERGE_LIST.equals(fileName)) {
+        // For the initial commit, we have an empty tree on Side A
+        RevObject object = rw.parseAny(patchList.getOldId());
+        a = object instanceof RevCommit
+            ? Text.forMergeList(patchList.getComparisonType(), reader, object)
+            : Text.EMPTY;
+        b = Text.forMergeList(patchList.getComparisonType(), reader, bCommit);
 
+        aTree = null;
+        bTree = null;
       } else {
         if (patchList.getOldId() != null) {
           aTree = rw.parseTree(patchList.getOldId());

gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchList.java

@@ -58,16 +58,19 @@ public class PatchList implements Serializable {
   @Nullable
   private transient ObjectId oldId;
   private transient ObjectId newId;
-  private transient boolean againstParent;
+  private transient boolean isMerge;
+  private transient ComparisonType comparisonType;
   private transient int insertions;
   private transient int deletions;
   private transient PatchListEntry[] patches;
 
-  public PatchList(@Nullable final AnyObjectId oldId, final AnyObjectId newId,
+  public PatchList(@Nullable AnyObjectId oldId, AnyObjectId newId,
-      final boolean againstParent, final PatchListEntry[] patches) {
+      boolean isMerge, ComparisonType comparisonType,
+      PatchListEntry[] patches) {
     this.oldId = oldId != null ? oldId.copy() : null;
     this.newId = newId.copy();
-    this.againstParent = againstParent;
+    this.isMerge = isMerge;
+    this.comparisonType = comparisonType;
 
     // We assume index 0 contains the magic commit message entry.
     if (patches.length > 1) {
@@ -97,9 +100,9 @@ public class PatchList implements Serializable {
     return Collections.unmodifiableList(Arrays.asList(patches));
   }
 
-  /** @return true if {@link #getOldId} is {@link #getNewId}'s ancestor. */
+  /** @return the comparison type */
-  public boolean isAgainstParent() {
+  public ComparisonType getComparisonType() {
-    return againstParent;
+    return comparisonType;
   }
 
   /** @return total number of new lines added. */
@@ -144,9 +147,12 @@ public class PatchList implements Serializable {
     if (Patch.COMMIT_MSG.equals(fileName)) {
       return 0;
     }
+    if (isMerge && Patch.MERGE_LIST.equals(fileName)) {
+      return 1;
+    }
 
     int high = patches.length;
-    int low = 1;
+    int low = isMerge ? 2 : 1;
     while (low < high) {
       final int mid = (low + high) >>> 1;
       final int cmp = patches[mid].getNewName().compareTo(fileName);
@@ -166,7 +172,8 @@ public class PatchList implements Serializable {
     try (DeflaterOutputStream out = new DeflaterOutputStream(buf)) {
       writeCanBeNull(out, oldId);
       writeNotNull(out, newId);
-      writeVarInt32(out, againstParent ? 1 : 0);
+      writeVarInt32(out, isMerge ? 1 : 0);
+      comparisonType.writeTo(out);
       writeVarInt32(out, insertions);
       writeVarInt32(out, deletions);
       writeVarInt32(out, patches.length);
@@ -182,7 +189,8 @@ public class PatchList implements Serializable {
     try (InflaterInputStream in = new InflaterInputStream(buf)) {
       oldId = readCanBeNull(in);
       newId = readNotNull(in);
-      againstParent = readVarInt32(in) != 0;
+      isMerge = readVarInt32(in) != 0;
+      comparisonType = ComparisonType.readFrom(in);
       insertions = readVarInt32(in);
       deletions = readVarInt32(in);
       final int cnt = readVarInt32(in);

gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchListKey.java

@@ -35,7 +35,7 @@ import java.io.Serializable;
 import java.util.Objects;
 
 public class PatchListKey implements Serializable {
-  public static final long serialVersionUID = 22L;
+  public static final long serialVersionUID = 24L;
 
   public static final BiMap<Whitespace, Character> WHITESPACE_TYPES = ImmutableBiMap.of(
       Whitespace.IGNORE_NONE, 'N',
@@ -138,6 +138,10 @@ public class PatchListKey implements Serializable {
     n.append("..");
     n.append(newId.name());
     n.append(" ");
+    if (parentNum != null) {
+      n.append(parentNum);
+      n.append(" ");
+    }
     n.append(whitespace.name());
     n.append("]");
     return n.toString();

gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchListLoader.java

@@ -16,7 +16,6 @@
 package com.google.gerrit.server.patch;
 
 import static com.google.common.base.Preconditions.checkArgument;
-
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static java.util.stream.Collectors.toSet;
 import static org.eclipse.jgit.lib.Constants.OBJ_BLOB;
@@ -156,14 +155,19 @@ public class PatchListLoader implements Callable<PatchList> {
 
       if (a == null) {
         // TODO(sop) Remove this case.
-        // This is a merge commit, compared to its ancestor.
+        // This is an octopus merge commit which should be compared against the
+        // auto-merge. However since we don't support computing the auto-merge
+        // for octopus merge commits, we fall back to diffing against the first
+        // parent, even though this wasn't what was requested.
         //
-        PatchListEntry[] entries = new PatchListEntry[1];
+        ComparisonType comparisonType = ComparisonType.againstParent(1);
+        PatchListEntry[] entries = new PatchListEntry[2];
         entries[0] = newCommitMessage(cmp, reader, null, b);
-        return new PatchList(a, b, true, entries);
+        entries[1] = newMergeList(cmp, reader, null, b, comparisonType);
+        return new PatchList(a, b, true, comparisonType, entries);
       }
 
-      boolean againstParent = isAgainstParent(a, b);
+      ComparisonType comparisonType = getComparisonType(a, b);
 
       RevCommit aCommit = a instanceof RevCommit ? (RevCommit) a : null;
       RevTree aTree = rw.parseTree(a);
@@ -190,7 +194,13 @@ public class PatchListLoader implements Callable<PatchList> {
       int cnt = diffEntries.size();
       List<PatchListEntry> entries = new ArrayList<>();
       entries.add(newCommitMessage(cmp, reader,
-          againstParent ? null : aCommit, b));
+          comparisonType.isAgainstParentOrAutoMerge() ? null : aCommit, b));
+      boolean isMerge = b.getParentCount() > 1;
+      if (isMerge) {
+        entries.add(newMergeList(cmp, reader,
+            comparisonType.isAgainstParentOrAutoMerge() ? null : aCommit, b,
+            comparisonType));
+      }
       for (int i = 0; i < cnt; i++) {
         DiffEntry e = diffEntries.get(i);
         if (paths == null || paths.contains(e.getNewPath())
@@ -204,19 +214,23 @@ public class PatchListLoader implements Callable<PatchList> {
           entries.add(newEntry(aTree, fh, newSize, newSize - oldSize));
         }
       }
-      return new PatchList(a, b, againstParent,
+      return new PatchList(a, b, isMerge, comparisonType,
           entries.toArray(new PatchListEntry[entries.size()]));
     }
   }
 
-  private boolean isAgainstParent(RevObject a, RevCommit b) {
+  private ComparisonType getComparisonType(RevObject a, RevCommit b) {
     for (int i = 0; i < b.getParentCount(); i++) {
       if (b.getParent(i).equals(a)) {
-        return true;
+        return ComparisonType.againstParent(i + 1);
       }
     }
 
-    return false;
+    if (key.getOldId() == null && b.getParentCount() > 0) {
+      return ComparisonType.againstAutoMerge();
+    }
+
+    return ComparisonType.againstOtherPatchSet();
   }
 
   private static long getFileSize(ObjectReader reader,
@@ -278,32 +292,30 @@ public class PatchListLoader implements Callable<PatchList> {
     return diffFormatter.toFileHeader(diffEntry);
   }
 
-  private PatchListEntry newCommitMessage(final RawTextComparator cmp,
+  private PatchListEntry newCommitMessage(RawTextComparator cmp,
-      final ObjectReader reader,
+      ObjectReader reader, RevCommit aCommit, RevCommit bCommit)
-      final RevCommit aCommit, final RevCommit bCommit) throws IOException {
+          throws IOException {
-    StringBuilder hdr = new StringBuilder();
+    Text aText = aCommit != null
-
+        ? Text.forCommit(reader, aCommit)
-    hdr.append("diff --git");
+        : Text.EMPTY;
-    if (aCommit != null) {
-      hdr.append(" a/").append(Patch.COMMIT_MSG);
-    } else {
-      hdr.append(" ").append(FileHeader.DEV_NULL);
-    }
-    hdr.append(" b/").append(Patch.COMMIT_MSG);
-    hdr.append("\n");
-
-    if (aCommit != null) {
-      hdr.append("--- a/").append(Patch.COMMIT_MSG).append("\n");
-    } else {
-      hdr.append("--- ").append(FileHeader.DEV_NULL).append("\n");
-    }
-    hdr.append("+++ b/").append(Patch.COMMIT_MSG).append("\n");
-
-    Text aText =
-        aCommit != null ? Text.forCommit(reader, aCommit) : Text.EMPTY;
     Text bText = Text.forCommit(reader, bCommit);
+    return createPatchListEntry(cmp, aCommit, aText, bText, Patch.COMMIT_MSG);
+  }
 
-    byte[] rawHdr = hdr.toString().getBytes(UTF_8);
+  private PatchListEntry newMergeList(RawTextComparator cmp,
+      ObjectReader reader, RevCommit aCommit, RevCommit bCommit,
+      ComparisonType comparisonType) throws IOException {
+    Text aText = aCommit != null
+        ? Text.forMergeList(comparisonType, reader, aCommit)
+        : Text.EMPTY;
+    Text bText =
+        Text.forMergeList(comparisonType, reader, bCommit);
+    return createPatchListEntry(cmp, aCommit, aText, bText, Patch.MERGE_LIST);
+  }
+
+  private static PatchListEntry createPatchListEntry(RawTextComparator cmp,
+      RevCommit aCommit, Text aText, Text bText, String fileName) {
+    byte[] rawHdr = getRawHeader(aCommit != null, fileName);
     byte[] aContent = aText.getContent();
     byte[] bContent = bText.getContent();
     long size = bContent.length;
@@ -315,6 +327,26 @@ public class PatchListLoader implements Callable<PatchList> {
     return new PatchListEntry(fh, edits, size, sizeDelta);
   }
 
+  private static byte[] getRawHeader(boolean hasA, String fileName) {
+    StringBuilder hdr = new StringBuilder();
+    hdr.append("diff --git");
+    if (hasA) {
+      hdr.append(" a/").append(fileName);
+    } else {
+      hdr.append(" ").append(FileHeader.DEV_NULL);
+    }
+    hdr.append(" b/").append(fileName);
+    hdr.append("\n");
+
+    if (hasA) {
+      hdr.append("--- a/").append(fileName).append("\n");
+    } else {
+      hdr.append("--- ").append(FileHeader.DEV_NULL).append("\n");
+    }
+    hdr.append("+++ b/").append(fileName).append("\n");
+    return hdr.toString().getBytes(UTF_8);
+  }
+
   private PatchListEntry newEntry(RevTree aTree, FileHeader fileHeader,
       long size, long sizeDelta) {
     if (aTree == null // want combined diff

gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchScriptBuilder.java

@@ -66,7 +66,7 @@ class PatchScriptBuilder {
   private ObjectReader reader;
   private Change change;
   private DiffPreferencesInfo diffPrefs;
-  private boolean againstParent;
+  private ComparisonType comparisonType;
   private ObjectId aId;
   private ObjectId bId;
 
@@ -79,7 +79,8 @@ class PatchScriptBuilder {
   private int context;
 
   @Inject
-  PatchScriptBuilder(final FileTypeRegistry ftr, final PatchListCache plc) {
+  PatchScriptBuilder(FileTypeRegistry ftr,
+      PatchListCache plc) {
     a = new Side();
     b = new Side();
     registry = ftr;
@@ -106,8 +107,8 @@ class PatchScriptBuilder {
     }
   }
 
-  void setTrees(final boolean ap, final ObjectId a, final ObjectId b) {
+  void setTrees(final ComparisonType ct, final ObjectId a, final ObjectId b) {
-    againstParent = ap;
+    comparisonType = ct;
     aId = a;
     bId = b;
   }
@@ -435,7 +436,8 @@ class PatchScriptBuilder {
       try {
         final boolean reuse;
         if (Patch.COMMIT_MSG.equals(path)) {
-          if (againstParent && (aId == within || within.equals(aId))) {
+          if (comparisonType.isAgainstParentOrAutoMerge()
+              && (aId == within || within.equals(aId))) {
             id = ObjectId.zeroId();
             src = Text.EMPTY;
             srcContent = Text.NO_BYTES;
@@ -453,7 +455,26 @@ class PatchScriptBuilder {
             }
           }
           reuse = false;
-
+        } else if (Patch.MERGE_LIST.equals(path)) {
+          if (comparisonType.isAgainstParentOrAutoMerge()
+              && (aId == within || within.equals(aId))) {
+            id = ObjectId.zeroId();
+            src = Text.EMPTY;
+            srcContent = Text.NO_BYTES;
+            mode = FileMode.MISSING;
+            displayMethod = DisplayMethod.NONE;
+          } else {
+            id = within;
+            src = Text.forMergeList(comparisonType, reader, within);
+            srcContent = src.getContent();
+            if (src == Text.EMPTY) {
+              mode = FileMode.MISSING;
+              displayMethod = DisplayMethod.NONE;
+            } else {
+              mode = FileMode.REGULAR_FILE;
+            }
+          }
+          reuse = false;
         } else {
           final TreeWalk tw = find(within);
 

gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchScriptFactory.java

@@ -260,7 +260,7 @@ public class PatchScriptFactory implements Callable<PatchScript> {
     b.setRepository(git, project);
     b.setChange(change);
     b.setDiffPrefs(diffPrefs);
-    b.setTrees(list.isAgainstParent(), list.getOldId(), list.getNewId());
+    b.setTrees(list.getComparisonType(), list.getOldId(), list.getNewId());
     return b;
   }
 

gerrit-server/src/main/java/com/google/gerrit/server/patch/Text.java

@@ -87,6 +87,36 @@ public class Text extends RawText {
     }
   }
 
+  public static Text forMergeList(ComparisonType comparisonType,
+      ObjectReader reader, AnyObjectId commitId) throws IOException {
+    try (RevWalk rw = new RevWalk(reader)) {
+      RevCommit c = rw.parseCommit(commitId);
+      StringBuilder b = new StringBuilder();
+      switch (c.getParentCount()) {
+        case 0:
+          break;
+        case 1: {
+          break;
+        }
+        default:
+          int uniterestingParent = comparisonType.isAgainstParent()
+              ? comparisonType.getParentNum()
+              : 1;
+
+          b.append("Merge List:\n\n");
+          for (RevCommit commit : MergeListBuilder.build(rw, c,
+              uniterestingParent)) {
+            b.append("* ");
+            b.append(reader.abbreviate(commit, 8).name());
+            b.append(" ");
+            b.append(commit.getShortMessage());
+            b.append("\n");
+          }
+      }
+      return new Text(b.toString().getBytes(UTF_8));
+    }
+  }
+
   private static void appendPersonIdent(StringBuilder b, String field,
       PersonIdent person) {
     if (person != null) {

gerrit-server/src/main/java/com/google/gerrit/server/project/FilesInCommitCollection.java

@@ -47,7 +47,7 @@ public class FilesInCommitCollection implements
   @Override
   public FileResource parse(CommitResource parent, IdString id)
       throws ResourceNotFoundException, IOException {
-    if (Patch.COMMIT_MSG.equals(id.get())) {
+    if (Patch.isMagic(id.get())) {
       return new FileResource(parent.getProject(), parent.getCommit(),
           id.get());
     }

gerrit-server/src/main/java/com/google/gerrit/server/query/change/ChangeData.java

@@ -599,7 +599,7 @@ public class ChangeData {
 
       r = new ArrayList<>(p.get().getPatches().size());
       for (PatchListEntry e : p.get().getPatches()) {
-        if (Patch.COMMIT_MSG.equals(e.getNewName())) {
+        if (Patch.isMagic(e.getNewName())) {
           continue;
         }
         switch (e.getChangeType()) {

gerrit-server/src/main/java/gerrit/PRED_commit_stats_3.java

@@ -14,8 +14,10 @@
 
 package gerrit;
 
+import com.google.gerrit.reviewdb.client.Patch;
 import com.google.gerrit.rules.StoredValues;
 import com.google.gerrit.server.patch.PatchList;
+import com.google.gerrit.server.patch.PatchListEntry;
 
 import com.googlecode.prolog_cafe.exceptions.PrologException;
 import com.googlecode.prolog_cafe.lang.IntegerTerm;
@@ -24,6 +26,8 @@ import com.googlecode.prolog_cafe.lang.Predicate;
 import com.googlecode.prolog_cafe.lang.Prolog;
 import com.googlecode.prolog_cafe.lang.Term;
 
+import java.util.List;
+
 /**
  * Exports basic commit statistics.
  *
@@ -48,7 +52,11 @@ public class PRED_commit_stats_3 extends Predicate.P3 {
     Term a3 = arg3.dereference();
 
     PatchList pl = StoredValues.PATCH_LIST.get(engine);
-    if (!a1.unify(new IntegerTerm(pl.getPatches().size() - 1),engine.trail)) { //Account for /COMMIT_MSG.
+    // Account for magic files
+    if (!a1.unify(
+        new IntegerTerm(
+            pl.getPatches().size() - countMagicFiles(pl.getPatches())),
+        engine.trail)) {
       return engine.fail();
     }
     if (!a2.unify(new IntegerTerm(pl.getInsertions()),engine.trail)) {
@@ -59,4 +67,14 @@ public class PRED_commit_stats_3 extends Predicate.P3 {
     }
     return cont;
   }
+
+  private int countMagicFiles(List<PatchListEntry> entries) {
+    int count = 0;
+    for (PatchListEntry e : entries) {
+      if (Patch.isMagic(e.getNewName())) {
+        count++;
+      }
+    }
+    return count;
+  }
 }