Comment 17 for bug 720525

I am seeing this bug, too. All I can add is that it seems to happen on a file which is not present in the original full backup. The original full backup can be restored (or at least does not bump out when restoring the directory where the file listed in the assertion error lives).

For the record, I am using Fedora and there is a bug in their bugzilla, too:
https://bugzilla.redhat.com/show_bug.cgi?id=901420

There is also another entry on lauchpad which I found when googling for this problem:
https://bugs.launchpad.net/ubuntu/+source/duplicity/+bug/1222661

Unfortunately, no resolution in any of these, but the problem looks pretty serious.