muchsync files renames

[David Mazieres]

So just to follow up a bit.  I looked into things a bit further, and
here is what I found with maildir.synchronize_flags set to true.

Initially, when you run "muchsync --init", it copies all the files to
your maildir, and for each file invokes
notmuch_message_tags_to_maildir_flag.  That changes the name of the
file, with the result that the sql database and the actual mail
directory end up out of sync.  That on it's own is not a big deal, but
it means that the next time muchsync, muchsync will have to rescan all
of the files, as their names are no longer correct.  That shouldn't
cause any extra traffic between the two machines, but it will require
time on the client.  That is likely the source of the delay you were
seeing.

However, if you C-c the client during this process, I still don't see
any problems arising that cause more links to be transferred between
machines.  So I'm kind of stumped about that part.

Maybe muchsync should create the original file name based on tags, so as
to avoid having to rescan in the common case.  I wish there were some
way of getting the renamed file after
notmuch_message_tags_to_maildir_flags.

David