I tried looking through the archives, but couldn't find a satisfying answer.
- Sean manages the GitHub repo. It's read only. It doesn't accept PRs. Issue tracking is disabled, (by convention, not settings.)
- Some underlying SVN repo is the true central repository. Sean integrates over that repository, the pushes to the GitHub repo.
- Contributions take place through emailed patches to Sean or MASON-INTEREST-L.
Did I get this right?