Detect new package which is restoring a removed package (package category+name matches an old one)

[thesamesam]

@mgorny and I were discussing how Gentoo handles last-rites and removed packages, and I noted that Fedora requires developers to announce on their mailing list that an ex-package is being revived. I'm not suggesting we do that, but it's often interesting to know if a package used to be in Gentoo, both to look at the old ebuild, but also to explore why it was removed (think e.g. licencing reasons).

mgorny suggested pkgcheck should be able to give an Info-level message when the new package name matches an entry in pkgcheck's git cache.

So, suppose someone tries to do:

mkdir -p dev-python/matplotlib-python2
git add dev-python/matplotlib-python2 && pkgdev commit # An info-level message should be given about restoring an old package

although I hope nobody would try to restore that one :)