Since I last paid attention, FreeBSD has moved its official source to a (self-hosted) Git repository, so I can clone and pull directly from their master version.
I'm currently resisting the temptation to keep a local copy of NetBSD source. I almost never look at it (sorry, NetBSD, you're the extra BSD), and NetBSD's official version seems to still be in CVS, although they have an official Github-hosted Git mirror.