Description Natalie Chen 2018-06-14 21:03:10 EDT

Problem:
Exception in thread "main" java.lang.IllegalStateException: Duplicate stages not allowed: 0 subtree/file
	at org.eclipse.jgit.dircache.DirCacheBuilder.bad(DirCacheBuilder.java:278)
	at org.eclipse.jgit.dircache.DirCacheBuilder.resort(DirCacheBuilder.java:268)
	at org.eclipse.jgit.dircache.DirCacheBuilder.finish(DirCacheBuilder.java:224)
	at org.eclipse.jgit.merge.ResolveMerger.mergeTrees(ResolveMerger.java:1144)
	at org.eclipse.jgit.merge.ResolveMerger.mergeImpl(ResolveMerger.java:345)
	at org.eclipse.jgit.merge.Merger.merge(Merger.java:258)
	at org.eclipse.jgit.merge.Merger.merge(Merger.java:211)
	at org.eclipse.jgit.merge.ThreeWayMerger.merge(ThreeWayMerger.java:126)

Steps to reproduce:
1. cd /path/to/test
2. git init
3. touch init && git add init
4. git commit -m 'init'
5. touch subtree
6. touch subtree-0
7. git add -A && git commit -m 'add file subtree'  => commit1
8. rm subtree
9. mkdir subtree
10. touch subtree/file
11. git add subtree/file
12. git commit -m 'add subtree/file' => commit2
13. Run the following code:

		RepositoryBuilder rb = new RepositoryBuilder() 
		.setGitDir(new File(/path/to/test/.git>))
		.readEnvironment()
		.findGitDir();
		try (Repository repo = rb.build();
		   RevWalk rw = new RevWalk(repo);) {
			RevCommit toMerge = rw.parseCommit(ObjectId.fromString(commit1));
			RevCommit mergeTip = rw.parseCommit(ObjectId.fromString(commit2));
			
			ResolveMerger m = (ResolveMerger) MergeStrategy.RECURSIVE.newMerger(repo, true);
			m.setObjectInserter(createDryRunInserter(repo));
	                boolean mergeable = m.merge(new AnyObjectId[] {mergeTip, toMerge});
                }