To have one git repo “inside” another, look at git submodules: http://git-scm.com/book/en/Git-Tools-Submodules
By making pychargify a submodule of your django project, specific revisions of your django project can be associated with specific revisions of your pychargify project. That can be really useful.
I’m not sure exactly what the dangers are of the approach you describe, but it doesn’t pass the smell test for me. I would recommend using the Git feature (submodules) that is designed specifically for this type of thing.