Merge branch 'stable-2.13'

* stable-2.13:
  Support for at-sign (@) in usernames
  VersionedMetaData: Fix deletion of last file in branch
  WatchConfig.Accessor: Add method to delete all watches of an account

Change-Id: I2630ebc2d6bc7c5b68d40f8da2361ae08570790b

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/api/group/GroupsIT.java

@@ -98,6 +98,17 @@ public class GroupsIT extends AbstractDaemonTest {
     assertMembers(g, u1, u2);
   }
 
+  @Test
+  public void addMembersWithAtSign() throws Exception {
+    String g = createGroup("users");
+    TestAccount u10 = accounts.create("u10", "u10@example.com", "Full Name 10");
+    TestAccount u11_at =
+        accounts.create("u11@something", "u11@example.com", "Full Name 11 With At");
+    TestAccount u11 = accounts.create("u11", "u11.another@example.com", "Full Name 11 Without At");
+    gApi.groups().id(g).addMembers(u10.username, u11_at.username);
+    assertMembers(g, u10, u11_at);
+  }
+
   @Test
   public void includeRemoveGroup() throws Exception {
     String p = createGroup("parent");

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/server/project/ProjectWatchIT.java

@@ -23,26 +23,38 @@ import com.google.gerrit.acceptance.NoHttpd;
 import com.google.gerrit.acceptance.PushOneCommit;
 import com.google.gerrit.acceptance.Sandboxed;
 import com.google.gerrit.acceptance.TestAccount;
+import com.google.gerrit.common.TimeUtil;
 import com.google.gerrit.common.data.Permission;
 import com.google.gerrit.extensions.api.changes.ReviewInput;
 import com.google.gerrit.extensions.api.changes.StarsInput;
 import com.google.gerrit.extensions.common.GroupInfo;
+import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.reviewdb.client.AccountGroup;
 import com.google.gerrit.reviewdb.client.Project;
+import com.google.gerrit.server.account.WatchConfig;
 import com.google.gerrit.server.account.WatchConfig.NotifyType;
+import com.google.gerrit.server.account.WatchConfig.ProjectWatchKey;
 import com.google.gerrit.server.git.NotifyConfig;
 import com.google.gerrit.server.git.ProjectConfig;
 import com.google.gerrit.server.mail.Address;
 import com.google.gerrit.testutil.FakeEmailSender.Message;
+import com.google.inject.Inject;
+import java.util.Collections;
 import java.util.EnumSet;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
+import java.util.Set;
 import org.eclipse.jgit.internal.storage.dfs.InMemoryRepository;
 import org.eclipse.jgit.junit.TestRepository;
 import org.junit.Test;
 
+
 @NoHttpd
 @Sandboxed
 public class ProjectWatchIT extends AbstractDaemonTest {
+  @Inject private WatchConfig.Accessor watchConfig;
+
   @Test
   public void newPatchSetsNotifyConfig() throws Exception {
     Address addr = new Address("Watcher", "watcher@example.com");
@@ -480,4 +492,34 @@ public class ProjectWatchIT extends AbstractDaemonTest {
     // assert email notification
     assertThat(sender.getMessages()).isEmpty();
   }
+
+  @Test
+  public void deleteAllProjectWatches() throws Exception {
+    Map<ProjectWatchKey, Set<NotifyType>> watches = new HashMap<>();
+    watches.put(ProjectWatchKey.create(project, "*"), ImmutableSet.of(NotifyType.ALL));
+    watchConfig.upsertProjectWatches(admin.getId(), watches);
+    assertThat(watchConfig.getProjectWatches(admin.getId())).isNotEmpty();
+
+    watchConfig.deleteAllProjectWatches(admin.getId());
+    assertThat(watchConfig.getProjectWatches(admin.getId())).isEmpty();
+  }
+
+  @Test
+  public void deleteAllProjectWatchesIfWatchConfigIsTheOnlyFileInUserBranch() throws Exception {
+    // Create account that has no files in its refs/users/ branch.
+    Account.Id id = new Account.Id(db.nextAccountId());
+    Account a = new Account(id, TimeUtil.nowTs());
+    db.accounts().insert(Collections.singleton(a));
+
+    // Add a project watch so that a watch.config file in the refs/users/ branch is created.
+    Map<ProjectWatchKey, Set<NotifyType>> watches = new HashMap<>();
+    watches.put(ProjectWatchKey.create(project, "*"), ImmutableSet.of(NotifyType.ALL));
+    watchConfig.upsertProjectWatches(id, watches);
+    assertThat(watchConfig.getProjectWatches(id)).isNotEmpty();
+
+    // Delete all project watches so that the watch.config file in the refs/users/ branch is
+    // deleted.
+    watchConfig.deleteAllProjectWatches(id);
+    assertThat(watchConfig.getProjectWatches(id)).isEmpty();
+  }
 }

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

@@ -45,7 +45,7 @@ import java.sql.Timestamp;
  */
 public final class Account {
   public static final String USER_NAME_PATTERN_FIRST = "[a-zA-Z0-9]";
-  public static final String USER_NAME_PATTERN_REST = "[a-zA-Z0-9._-]";
+  public static final String USER_NAME_PATTERN_REST = "[a-zA-Z0-9._@-]";
   public static final String USER_NAME_PATTERN_LAST = "[a-zA-Z0-9]";
 
   /** Regular expression that {@link #userName} must match. */

gerrit-server/src/main/java/com/google/gerrit/server/git/VersionedMetaData.java

@@ -281,12 +281,7 @@ public abstract class VersionedMetaData {
           return;
         }
 
-        // Reuse tree from parent commit unless there are contents in newTree or
-        // there is no tree for a parent commit.
-        ObjectId res =
-            newTree.getEntryCount() != 0 || srcTree == null
-                ? newTree.writeTree(inserter)
-                : srcTree.copy();
+        ObjectId res = newTree.writeTree(inserter);
         if (res.equals(srcTree) && !update.allowEmpty() && (commit.getTreeId() == null)) {
           // If there are no changes to the content, don't create the commit.
           return;