I still see github pull requests rather frequently, even though they have never been allowed. All discussion AND patches go through the mailing list, much like the linux kernel.
It's unfortunate that github doesn't let a project disable the on-website UI for pull request submission; as it is it's easy for somebody to end up wasting their time trying to submit a change that way. (QEMU has that issue too.)
If you are at all interested in hacking on Git, it's not that difficult. Knowing C and portable shell scripting for writing tests are the big things.
One sticking point, you need to submit patches to the mailing list, you can't just do a github pull request.
See https://github.com/git/git/blob/master/Documentation/Submitt...
I still see github pull requests rather frequently, even though they have never been allowed. All discussion AND patches go through the mailing list, much like the linux kernel.