ValueError: Unsupported date format
https://github.com/gitpython-developers/GitPython/blob/c6e0a6cb5c70efd0899f620f83eeebcc464be05c/git/objects/util.py#L131
https://github.com/gitpython-developers/GitPython/blob/f3265bd8beb017890699d093586126ff8af4a3fe/git/objects/commit.py#L348
It doesn't work. I have tried passing a datetime object into commit, I have tried passing an integer timestamp, I have tried converting it into a string (both isoformat and ctime) and passing it, and nothing worked.
Finally I have managed to make it accept the datetime using some nasty hack with strings slicing.
I guess that the code is flawed, it shouldn't be so unusable and it should work with python datetime objects. Why don't you use dateutil.parser?
In a dynamically typed language, things like this may always happen. As a low-level function is used, one must expect it to only deal gracefully with input exactly as it expects it, without making conversions.
If you are willing to look elsewhere, eventually grit might just be what you need.