git-annex-shell inannex now returns always 0, 1, or 100 (the last when
it's unclear if content is currently in the index due to it currently being
moved or dropped).
(Actual locking code still not yet written.)
The lock will only persist during the perform stage, so the content must
be removed from the annex then, rather than in the cleanup stage.
(No lock is actually taken yet.)
