It's a heavily modified internal fork of Django. Source: I work on our Python Language Foundation team.
If so, do you have any recommendations or suggestions for someone getting their feet wet on this?
Some of my team mates work on driving internal adoption of Cinder, rolling out new versions of Python everywhere, improvements to our build and packaging systems, supporting other Python tooling teams, etc. There's a lot of cross-functional project work, and our primary goal is to improve the Python developer experience, both internally and externally wherever we can.