root@ubuntu:/# do-release-upgrade
Traceback (most recent call last):
  File "/usr/bin/do-release-upgrade", line 10, in <module>
    from UpdateManager.Core.DistUpgradeFetcherCore import DistUpgradeFetcherCore
  File "/usr/lib/python2.6/dist-packages/UpdateManager/Core/DistUpgradeFetcherCore.py", line 34, in <module>
    import GnuPGInterface
ImportError: No module named GnuPGInterface