Patch to avoid mailboxesdb corruption on concurrent renames

[Ken Murchison]

Bron Gondwana wrote:

> Bron ( P.S. isn't it about time for a 2.3.12?  I'm getting sick
>        of posting skiplist patches to people running the
>        lastest and having issues! )

Yes, it probably is.  Perhaps I'll make a pre-release today while I 
troll bugzilla for any showstoppers.

-- 
Kenneth Murchison
Systems Programmer
Project Cyrus Developer/Maintainer
Carnegie Mellon University