CommitMergeStatus: Remove REVISION_GONE and NO_PATCH_SET

That these were only set on special sentinel CodeReviewCommits with no
SHA-1 attached was a smell that they don't really belong as status of
a commit per se. Since the recent MergeOp refactorings, we now use a
more descriptive error in every case where we used to set these values
on commits; they are now dead code and can be removed.

Change-Id: I8a14ac1684b68c838bd238a47f025a2aa8a138fc

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

@@ -26,7 +26,6 @@ import com.google.gerrit.server.project.ChangeControl;
 import org.eclipse.jgit.errors.IncorrectObjectTypeException;
 import org.eclipse.jgit.errors.MissingObjectException;
 import org.eclipse.jgit.lib.AnyObjectId;
-import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.ObjectReader;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.RevCommit;
@@ -63,33 +62,6 @@ public class CodeReviewCommit extends RevCommit {
     return new CodeReviewRevWalk(reader);
   }
 
-  static CodeReviewCommit revisionGone(ChangeControl ctl) {
-    return error(ctl, CommitMergeStatus.REVISION_GONE);
-  }
-
-  static CodeReviewCommit noPatchSet(ChangeControl ctl) {
-    return error(ctl, CommitMergeStatus.NO_PATCH_SET);
-  }
-
-  /**
-   * Create an error commit.
-   * <p>
-   * Should only be used for error statuses such that there is no possible
-   * non-zero commit on which we could call {@link
-   * #setStatusCode(CommitMergeStatus)}, enumerated in the methods above.
-   *
-   * @param ctl control for change that caused this error
-   * @param s status
-   * @return new commit instance
-   */
-  private static CodeReviewCommit error(ChangeControl ctl,
-      CommitMergeStatus s) {
-    CodeReviewCommit r = new CodeReviewCommit(ObjectId.zeroId());
-    r.setControl(ctl);
-    r.statusCode = s;
-    return r;
-  }
-
   public static class CodeReviewRevWalk extends RevWalk {
     private CodeReviewRevWalk(Repository repo) {
       super(repo);

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

@@ -41,12 +41,6 @@ public enum CommitMergeStatus {
   /** */
   MISSING_DEPENDENCY(""),
 
-  /** */
-  NO_PATCH_SET(""),
-
-  /** */
-  REVISION_GONE(""),
-
   /** */
   MANUAL_RECURSIVE_MERGE("The change requires a local merge to resolve.\n"
                        + "\n"

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

@@ -890,11 +890,6 @@ public class MergeOp implements AutoCloseable {
           problems.put(id, "depends on change that was not submitted");
           break;
 
-        case REVISION_GONE:
-          // TODO(dborowitz): Should no longer be generated by built-in code;
-          // finish removing.
-          throw new IllegalStateException();
-
         default:
           problems.put(id, "unspecified merge failure: " + s);
           break;