headName = "detached HEAD";
ObjectId headId = head.getObjectId();
if (headId == null)
throw new RefNotFoundException(MessageFormat.format(
JGitText.get().refNotResolved, Constants.HEAD));
RevCommit headCommit = walk.lookupCommit(headId);
RevCommit upstream = walk.lookupCommit(upstreamCommit.getId());
if (!isInteractive() && walk.isMergedInto(upstream, headCommit))
return RebaseResult.UP_TO_DATE_RESULT;
else if (!isInteractive() && walk.isMergedInto(headCommit, upstream)) {
// head is already merged into upstream, fast-foward