sys-process/htop has runtime dev-lang/python dependence (in fact python is only required at build time)
Well, the ebuild has it in DEPEND rather than BDEPEND, but not RDEPEND right now.
Skimming, I don't see it there in the past, but maybe I missed it. https://gitweb.gentoo.org/repo/gentoo.git/commit/sys-process/htop?id=d6addd0be0d88d49fdbb175030312b3283bfb88f is kind of relevant.
Is this still a problem?