Comment 2 for bug 1061101

For what it is worth I wasn't able to recreate this using the same package version and command on quantal. I wonder if you tried to add the ppa immediately after creating it in Launchpad and that may have caused an issue.

Looking at it some more I guess something like this would fix it:

if signing_key_fingerprint is None:
    return False

after the try, except for getting the key fingerprint.