About 5½ years ago, the decision was made <http://lwn.net/Articles/326201/> to use Mercurial as the preferred version-control system (VCS) for Python development. It was already clear at the time that there was a strong preference among developers for Git instead of Mercurial. And since that time, the dominance of Git has only grown. It appears that Mercurial is still the official VCS for at least the CPython core, but the Python project already has a GitHub area <https://github.com/python> which includes a “Semi-official read-only mirror of the CPython Mercurial repository”. I would suspect that a lot of their contributors are already doing their work in Git, and communicating with the upstream Mercurial repo using an addon like git-remote-hg, which makes it look just like a native Git repo. Now there is a plan to migrate at least some supporting repositories <http://lwn.net/Articles/624101/> <http://lwn.net/Articles/623905/> officially to Git, and also use GitHub to host these instead of at python.org. These stats from the PEP are quite interesting: The Open Hub (Previously Ohloh) statistics ... show that currently 37% of the repositories Open Hub is indexing is using git which is second only to SVN (which has 48%) while Mercurial has just 2% of the indexed repositories (beating only bazaar which has 1%). In addit[i]on to the Open Hub statistics a look at the top 100 projects on PyPI (ordered by total download counts) shows us that within the Python space itself there is a majority of projects using git: === ========= ========== ====== === ==== Git Mercurial Subversion Bazaar CVS None === ========= ========== ====== === ==== 62 22 7 4 1 1 === ========= ========== ====== === ==== Interesting that Subversion (aka SVN, an older, centralized, much less flexible version-control system) manages to handily beat Mercurial in non-Python-specific projects...