private Collection<Ref> filterRefs(Collection<Ref> refs)
  throws RefNotFoundException, IOException {
		if (containsCommitish == null)
			return refs;

		try (RevWalk walk = new RevWalk(repo)) {
			ObjectId resolved = repo.resolve(containsCommitish);
			if (resolved == null)
				throw new RefNotFoundException(MessageFormat.format(
						JGitText.get().refNotResolved, containsCommitish));

			RevCommit containsCommit = walk.parseCommit(resolved);
			return RevWalkUtils.findBranchesReachableFrom(containsCommit, walk,
					refs);
		}
	}