import functools
def f():
    def g():
        yield 1
    return g

functools.partial(f())().__qualname__ != f()().__qualname__

The qualified name gets passed in via the interpreter loop with _PyEval_EvalCodeWithName calling PyGen_NewWithQualName.  If a generator object gets called from C then the qualified name gets lost.

It seems like _PyEval_EvalCodeWithName shouldn't exist and the generator code object should be able to get back to its qualified name so subtle differences like this don't happen.