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.
See #17273 (moved) for design component of this. Does not need to be merged into 0.2.8, but needs to be done on a similar timeframe.
Due April 2016