I have this bug too. Exactly the same error. Thank god I didn't suffer from the last 2 upgrade issues.
/me pokes the QA team -- Flashplugin-nonfree in backports fails to install https://launchpad.net/bugs/61404 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
