[Duplicity-talk] interrupted backup can't resume

[Ryan Meador]

Hi all,
Last night I had some sort of network hiccup while my nightly backup was
running and it was interrupted.  Duplicity seems unable to resume,
giving me a "bad passphrase" error message.  I think this is the same
issue that is reported here:
https://bugs.launchpad.net/duplicity/+bug/946988

I can't figure a few things out, however.  I don't believe I'm signing
(I specify only --encrypt-key on the command line), and it's a public
key, so why would it need my passphrase to continue encrypting things?
It didn't need it to encrypt the files the first time around.  Secondly,
if it needs my passphrase, why isn't it prompting me for it?  I have GPG
set up to "use-agent", which for any other purpose prompts me with a
nice GUI dialog for the passphrase whenever it needs it.  I even tried
getting gpg-agent to cache my passphrase and then I ran the backup, and
still it failed.  I'd love to understand why.

Is there a workaround for this issue?  If I run "duplicity cleanup" will
it remove the partial backup and allow me to do it all over again
(without removing old completed backups)?  What might be the correct
syntax for that?

Here's the output containing the error message:
Local and Remote metadata are synchronized, no sync needed.
Last full backup left a partial set, restarting.
Last full backup date: Fri Aug 17 03:00:02 2012
RESTART: Volumes 2 to 3 failed to upload before termination.
         Restarting backup at volume 2.
GPGError: GPG Failed, see log below:
===== Begin GnuPG log =====
gpg: encrypted with 2048-bit RSA key, ID 3289D83A, created 2012-03-09
"Ryan Meador (Platform Engineer) <address@hidden>"
gpg: public key decryption failed: bad passphrase
gpg: decryption failed: secret key not available
===== End GnuPG log =====

Thanks,
Ryan