Use CPAN is the core version is eaual to the CPAN version

In order to avoid edge conditions where the latest core has something
that matches CPAN, but the older ones don't, use CPAN when they match.
This will avoid getting different dependencies for the varoous cores,
and increase the chance that we can deduplicate the installs into
common.
fixup! Use CPAN is the core version is eaual to the CPAN version