Error importing Trac bugwatch comments - no comment owner

[Eleanor Berger]

When trying to sync bug watches with a remote Trac, I got the following error:

2008-10-14 14:37:35 INFO creating lockfile
2008-10-14 14:37:46 INFO Updating 2 watches on http://trac.intellectronica.net
2008-10-14 14:37:53 ERROR Failure updating bug u'1' on http://trac.intellectronica.net (local bugs: 34567, 33333). (OOPS-1018SCW4)
2008-10-14 14:37:53 INFO Time for this run: 8.694 seconds.
2008-10-14 14:37:53 DEBUG Removing lock file: /var/lock/launchpad-checkwatches.lock

$ cat ../../staging-logs/2008-10-14/52673.SCW4
Oops-Id: OOPS-1018SCW4
Exception-Type: AttributeError
Exception-Value: 'NoneType' object has no attribute 'displayname'
Date: 2008-10-14T14:37:53.890672+00:00
Page-Id:
Branch: launchpad
Revision: 7178
User: None
URL: http://trac.intellectronica.net/ticket/1
Duration: -1

URL=http://trac.intellectronica.net/ticket/1
baseurl=http://trac.intellectronica.net
batch_query_threshold=10
batch_size=100
bug_id=1
error-explanation=Failure updating bug u%271%27 on http://trac.intellectronica.net (local bugs: 34567, 33333).
externalbugtracker=TracLPPlugin
local_ids=34567, 33333
sync_comments=True

Traceback (most recent call last):
  Module canonical.launchpad.scripts.checkwatches, line 519, in updateBugWatches
    self.importBugComments(remotesystem, bug_watch)
  Module canonical.launchpad.scripts.checkwatches, line 670, in importBugComments
    commenter=comment.owner.displayname,
AttributeError: 'NoneType' object has no attribute 'displayname'
launchpad@asuka:/srv/staging.launchpad.net/staging/launchpad$

[Graham Binns (gmb)]

Landed in r7183.