I've fallen completely out of practice on this dev blog, but I felt I had
to mention a major milestone accomplished over the past week. The database
that git-annex maintains about keys and worktree files used to only be
guaranteed to be maintained for unlocked files, but it did not have
information about locked files. Now it does, and it's automatically, and
efficiently (I hope) kept up-to-date.

That let a long-standing bug get fixed, where when 2 files used the same
key, the preferred content expression could match one file and not the
other and cause get/drop to happen over and over. 

But there are probably a lot of other ways this database could be used, now
that's it's fully available. For example, it would be easy to write a
git-annex command that queries for which worktree files use a key, without
needing to scan the whole worktree to find them.
