FWIW, on Gentoo, the realpath package used is the one from
Debian.
Well, not really used anymore, because realpath is in coreutils now (since January of this year, according to the ChangeLog [coreutils-8.15])...
.
I'm starting to realize that the only distro that manages to somewhat keep up with Gentoo ~arch on the bleeding edge side of things is Arch...