First, I hope Guile can use gitlab.
However, IIRC, RMS has some comments on this, the hosting service must be free, and it shouldn't allow to fork, but branch-based. This is reasonable to protect project, but RMS speaks as a skilled hacker, I have to say it's very good policy in a professional engineers team to be branch-based.
But nowadays, people hope FOSS project be easier to contribute, fork is easier for them.
I accept patches on Gitlab for GNU Artanis.
BTW, that's the main reason I write GNU Artanis, since I'd like to provide a new Savannah to provide modern services and abey FSF ethic. Although it's in a very slow stepping toward to final target...