No time to blog yesterday, but I somehow found the time to fix the second
to last known major issue with v6 mode, a database inconsistency problem
involving touching annexed files.

The only remaining blocker for v6 not being experimental is that `git
checkout` of large unlocked files can use a lot of memory (and doesn't
honor annex.thin).

Also I finally have a rought plan for how to [[todo/hide_missing_files]]:
Have `git annex sync` update the working tree to only show visible files.
Still details to work out, but it would be great to finally get this
often-requested feature.
