[PATCH 00/10] Fix 'notmuch new' atomicity issues

[Austin Clements]

This patch series modifies notmuch new to perform all operations
atomically and to perform maildir flag synchronization eagerly.  As a
result, notmuch new can be interrupted without risking database
consistency or losing track of messages, but still without losing
progress in the middle of a big import.  This also paves the way for
fixing the antisocial locking behavior of notmuch new.

While there are quite a few patches in the series, each one is
bite-sized and you can see the number of atomicity violations dropping
with nearly every patch using the test added by the first patch.

On my test machine, these patches have no affect on performance.

These patches are also available on the atomic-new-v1 branch at
 http://awakening.csail.mit.edu/git/notmuch.git/