Duplicity - "Fatal Error: Backup source host has changed."

[gonk]

I saw that all of my duplicity jobs had failed with the following reason stated.

Fatal Error: Backup source host has changed.
Current hostname: B3
Previous hostname: B3.localdomain

Aborting because you may have accidentally tried to backup two different data sets to the same remote location, or using the same archive directory. If this is not a mistake, use the --allow-source-mismatch switch to avoid seeing this message

I have not changed the host name.
What has caused these failures?
How do I fix them?

The last restore point listed is "Mon, 24 Jun 2013 10:00:16 +0000"

Was that made in the update to 2.6?
If so please pay attention and fix this so that users aren't falsely assuming that their old backup jobs are still functional.

How do I set the affected jobs to "use the --allow-source-mismatch switch"?

[johannes]

HI Gonk, this was strange. We have tested this quote thoroughly and not seen this behavior. However it is known that the old backup system had issues, so I suggest you abandon that and create a backup job in the new backup system.

Meanwhile we'll try to get more error reports on this to figure out what can be the issue here.

[gonk]

If you need any more information then just reply and I'll help you cecause Duplicity failing this way is not ok.