I tried looking through the archives, but couldn't find a satisfying answer. 

AFAICT: 

- 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?

// Johnny