OK, from your link, it looks like the only problem affecting atomic snapshots is that `.git/index.lock` could be left in existence which will block git from doing any operations until it is deleted. For some reason git will instruct the user to delete this file but will not do it automatically, even though it could actually check if any live processes have the file locked, and assume that, if not, it is stale.

Seems like a bug in git IMO, but still reasonably easy to recover from.