GitLab is used only for code review, issue tracking and project management. Canonical locations for source code are still https://gitweb.torproject.org/ https://git.torproject.org/ and git-rw.torproject.org.
Due to https://github.com/torproject/stem/issues/63 our CI is failing. Let's downgrade to a working version of Stem unless it gets fixed right away.
I have a test PR at https://github.com/torproject/tor/pull/1889 ; if CI passes, I'll make PRs for the other branches and put this in needs_review.