I'm on Karmic Koala, upgrading to Lucid Lynx.
I renamed all of the /usr/local/lib/libreadline* to /usr/local/lib/badreadline*
sudo mv libreadline.old badlibreadline.old
sudo mv libreadline.so...
I fixed it in the absolute worst way. I changed the file
/usr/lib64/python2.6/dist-packages/UpdateManager/Core/DistUpgradeFetcherCore.py
Line 104: return False
to:
104 # REALLY BAD...
The problem wasn't gpg after all, but libreadline6. Updating it didn't help, but building it manually (md5: a3a5bf025a1b8df869f45f34098ffc6a rather than...