I think that git-recover-repository is ready now. Made it deal with the
index file referencing corrupt objects. The best approach I could think of
for that is to just remove those objects from the index, so the user can
re-add files from their work tree after recovery.

Now to integrate this git repository repair capability into the git-annex 
assistant. I decided to run `git fsck` as part of a scheduled
repository consistency check. It may also make sense for the assistant to
notice when things are going wrong, and suggest an immediate check. I've
started on the webapp UI to run a repository repair when fsck detects
problems.

[[!img /assistant/brokenrepositoryalert.png]]

[[!img /assistant/repairrepository.png]]

[[!meta title="the user interface I hope noone ever sees"]]
