The root cause has been fixed, and as per bug 613698 there's now a repair tool available in trunk.
If you have an affected repository, get a copy of bzr trunk (bzr branch lp:bzr), and run "bzr reconcile --canonicalize-chks" on the affected repository.
(I'll copy that instruction into the description of this bug to help people find it.)
The root cause has been fixed, and as per bug 613698 there's now a repair tool available in trunk.
If you have an affected repository, get a copy of bzr trunk (bzr branch lp:bzr), and run "bzr reconcile --canonicalize- chks" on the affected repository.
(I'll copy that instruction into the description of this bug to help people find it.)