in reply to
upgrade broke perl?
That's a bit not related, but imho, do-release-upgrade in 10.04 is totaly broken, so it not worth fixing perl
I tried it on just-installed brand new ubuntu 10.04 desktop - it failed. (however it worked fine when I logged out from GUI - still a bug, I did not receive any notice that I must shutdown GUI)
I tried it on my real 10.04 (without GUI), and of course I ended up with complete reinstall (I've got lots of funny messages - like "unknown version Ubuntu 12.04", "wrong GCC version", "cannot compile kernel", "there were some errors - exit or continue")
Perhaps for server distribution it works better, but for GUI it just don't work unless you did not touch anything (did not edit configs, did not workaround bugs, did not install software from source, etc) in the system after install