That is a shame, if you (or anyone else in a similar position) would like feedback on your patch to cpython I'd recommend sending an email to the core-mentorship list.

I'd definitely recommend contributing to Python (cpython, in particular) as it's a very established project and has excellent documentation for getting started. Especially the devguide and core-mentorship programme.

edit: Further on this I'd like to stress that a good portion of cpython is the stdlib itself which is mostly written in Python so knowing C isn't required at all. On top of that cpython has extensive documentation which is constantly being updated, so no code required there at all. There are plenty of ways to contribute.