This fixes#9610.
pytest 7.0.0 (unintentionally) changed `UnitTestFunction.obj`'s' behavior
to match `Function.obj`. That is probably a good thing to have, however
it evidently causes some regressions as described in the issue, so
restore the previous behavior for now. In the future we might want to
make this change again, but with proper consideration.
Ran Benita