Seeing lots of Key Error messages lately

[John Wiegley]

Sebastian,

I upgraded my spaetz/next a few days ago, to 7f22d89, and I'm now seeing lots
of KeyErrors:

--8<---------------cut here---------------start------------->8---
Deleting 10 messages (4419:4428) in MappedIMAP[Lists.WG21.Reflector]
ERROR: Syncing folder Lists/WG21/Reflector [acc: Gmail]
  4420
ERROR: ERROR in syncfolder for Gmail folder Lists/WG21/Reflector: Traceback (most recent call last):
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/offlineimap/accounts.py", line 431, in syncfolder
    remotefolder.syncmessagesto(localfolder, statusfolder)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/offlineimap/folder/Base.py", line 474, in syncmessagesto
    action(dstfolder, statusfolder)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/offlineimap/folder/Base.py", line 386, in syncmessagesto_delete
    folder.deletemessages(deletelist)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/offlineimap/folder/UIDMaps.py", line 277, in deletemessages
    self._mb.deletemessages(self._uidlist(self.r2l, uidlist))
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/offlineimap/folder/UIDMaps.py", line 85, in _uidlist
    return [mapping[x] for x in items]
KeyError: 4420

  4420
--8<---------------cut here---------------end--------------->8---

These happen 10-20 times a day.  I'm also seeing messages come back as
"unread" in my mailing lists, even though I remember marking them as read.

Thanks,
  John