Are you suggesting that GitHub should fork git to add new features?

Not needed. They already know how to use special repo branches for special things. See e.g. gh-pages and yourproject.wiki.git. They could _trivially_ have yourproject.issues.git etc, except that not doing that gives them a competitive moat making it harder to migrate away.

No of course.

Have you seen how github wikis work? Their backend is anoth git repo, with markdown files. Very nice for backups and change detection.

Same method can be appplied to configuration. Separate repo with json files or something.

Google's Gerrit Code Review stores its special permissions and such in a meta/ references namespace, which has restricted permissions. So instead of refs/heads/ for branch names, there's refs/meta/*. The meta space has config files specifying the permissions.

Also the config and permissions changes are logged, because they're git commits too.

The same could be done without forking git. One could also just have a parallel git repo with config files.