I realize this has been awhile but… I had trouble installing
Starman on Ubuntu 12 just now.
Net::Server::PreFork was "up to date" which actually meant it just had an undef VERSION so didn't know to update it. After updating it with
cpanm Net::Server::PreFork --reinstall Starman went in easily. Don't know if it's related to anything mentioned in this thread but there you have it.