One can no longer cleanly do cpan Bundle::CPAN on a fresh install of CentOS 6. Some dependencies don't install properly. I had to do the following:
cpan CPAN::Meta::YAML Parse::CPAN::Meta cpan Test::YAML cpan Compress::Raw::Zlib cpan Spiffy Test::Base cpan Module::Metadata CPAN::Meta Perl::OSType version cpan Compress::Raw::Bzip2 cpan Sub::Identify cpan SUPER cpan Test::MockModule cpan Bundle::CPAN
At least I didn't have to go into /root/.cpan and install things by hand.