Provide merge result when revert command fails

This allows callers to determine why the revert
did not complete successfully

Change-Id: Ie44bb8523cac388b63748bc69ebdd3c3a3665d06
Signed-off-by: Kevin Sawicki <kevin@github.com>

org.eclipse.jgit/src/org/eclipse/jgit/api/RevertCommand.java

@@ -46,8 +46,10 @@ import java.io.IOException;
 import java.text.MessageFormat;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.Map;
 
 import org.eclipse.jgit.JGitText;
+import org.eclipse.jgit.api.MergeResult.MergeStatus;
 import org.eclipse.jgit.api.errors.GitAPIException;
 import org.eclipse.jgit.api.errors.MultipleParentsNotAllowedException;
 import org.eclipse.jgit.api.errors.JGitInternalException;
@@ -62,6 +64,7 @@ import org.eclipse.jgit.lib.Ref.Storage;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.merge.MergeStrategy;
 import org.eclipse.jgit.merge.ResolveMerger;
+import org.eclipse.jgit.merge.ResolveMerger.MergeFailureReason;
 import org.eclipse.jgit.revwalk.RevCommit;
 import org.eclipse.jgit.revwalk.RevWalk;
 import org.eclipse.jgit.treewalk.FileTreeIterator;
@@ -81,6 +84,8 @@ public class RevertCommand extends GitCommand<RevCommit> {
 
 	private List<Ref> revertedRefs = new LinkedList<Ref>();
 
+	private MergeResult failingResult;
+
 	/**
 	 * @param repo
 	 */
@@ -155,6 +160,15 @@ public class RevertCommand extends GitCommand<RevCommit> {
 							.setReflogComment("revert: " + shortMessage).call();
 					revertedRefs.add(src);
 				} else {
+					Map<String, MergeFailureReason> failingPaths = merger
+							.getFailingPaths();
+					if (failingPaths != null)
+						failingResult = new MergeResult(null,
+								merger.getBaseCommit(0, 1),
+								new ObjectId[] { headCommit.getId(),
+										srcParent.getId() },
+								MergeStatus.FAILED, MergeStrategy.RESOLVE,
+								merger.getMergeResults(), failingPaths, null);
 					return null;
 				}
 			}
@@ -210,4 +224,12 @@ public class RevertCommand extends GitCommand<RevCommit> {
 	public List<Ref> getRevertedRefs() {
 		return revertedRefs;
 	}
+
+	/**
+	 * @return the result of the merge failure, <code>null</code> if no merge
+	 *         failure occurred during the revert
+	 */
+	public MergeResult getFailingResult() {
+		return failingResult;
+	}
 }