[3.9] bpo-45678: Add ``functools.singledispatchmethod`` tests (GH-29328) by miss-islington · Pull Request #29391 · python/cpython

This is fun! @ambv, it appears that attempting to backport these new tests to 3.9 has uncovered a bug in the 3.9 branch, where staticmethod and classmethod singledispatchmethods don't properly wrap the docstrings or names of the target function. Would the best course of action be to:

1. Abandon backporting this to 3.9?
2. Apply a bugfix along with the new tests to 3.9, linking to the same BPO issue?
3. Create a new BPO issue for a bugfix?