bug 48776, bug 40552 and bug 47095 are all related, the effect is the same and possibly the root cause as well.
-- [dist-upgrader] Cannot install "ubuntu-desktop" when upgrading from Breezy to Dapper Beta https://launchpad.net/bugs/40552 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
