Fix fast forward rebase with rebase.autostash=true

The folder .git/rebase-merge was not removed in this case. The
repository was then still in rebase state, but neither abort nor
continue worked.

Bug: 425742
Change-Id: I43cea6c9e5f3cef9d6b15643722fddecb40632d9

org.eclipse.jgit.test/tst/org/eclipse/jgit/api/RebaseCommandTest.java

@@ -1737,6 +1737,45 @@ public class RebaseCommandTest extends RepositoryTestCase {
 		assertEquals("file1", diffs.get(0).getOldPath());
 	}
 
+	@Test
+	public void testFastForwardRebaseWithAutoStash() throws Exception {
+		// create file0, add and commit
+		db.getConfig().setBoolean(ConfigConstants.CONFIG_REBASE_SECTION, null,
+				ConfigConstants.CONFIG_KEY_AUTOSTASH, true);
+		writeTrashFile("file0", "file0");
+		git.add().addFilepattern("file0").call();
+		git.commit().setMessage("commit0").call();
+		// create file1, add and commit
+		writeTrashFile(FILE1, "file1");
+		git.add().addFilepattern(FILE1).call();
+		RevCommit commit = git.commit().setMessage("commit1").call();
+
+		// create topic branch
+		createBranch(commit, "refs/heads/topic");
+
+		// checkout master branch / modify file1, add and commit
+		checkoutBranch("refs/heads/master");
+		writeTrashFile(FILE1, "modified file1");
+		git.add().addFilepattern(FILE1).call();
+		git.commit().setMessage("commit3").call();
+
+		// checkout topic branch / modify file0
+		checkoutBranch("refs/heads/topic");
+		writeTrashFile("file0", "unstaged modified file0");
+
+		// rebase
+		assertEquals(Status.FAST_FORWARD,
+				git.rebase().setUpstream("refs/heads/master")
+				.call().getStatus());
+		checkFile(new File(db.getWorkTree(), "file0"),
+				"unstaged modified file0");
+		checkFile(new File(db.getWorkTree(), FILE1), "modified file1");
+		assertEquals("[file0, mode:100644, content:file0]"
+				+ "[file1, mode:100644, content:modified file1]",
+				indexState(CONTENT));
+		assertEquals(RepositoryState.SAFE, db.getRepositoryState());
+	}
+
 	private List<DiffEntry> getStashedDiff() throws AmbiguousObjectException,
 			IncorrectObjectTypeException, IOException, MissingObjectException {
 		ObjectId stashId = db.resolve("stash@{0}");

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

@@ -281,6 +281,9 @@ public class RebaseCommand extends GitCommand<RebaseResult> {
 					return RebaseResult.INTERACTIVE_PREPARED_RESULT;
 				if (res != null) {
 					autoStashApply();
+					if (rebaseState.getDir().exists())
+						FileUtils.delete(rebaseState.getDir(),
+								FileUtils.RECURSIVE);
 					return res;
 				}
 			}