mock.patch cannot import an invalid-name module in >=3.11 due to importlib.import_module vs pkgutil.resolve_name differences when module has a dash in its filename

Bug report

importlib.import_module() and pkgutil.resolve_name() are inconsistent with regards to which formats they accept. For example, if I have a module that contains a dash (-) in its filename (for example in a Django management command), importlib.import_module() is able to import the module just fine, while pkgutil.resolve_name() will raise an exception about an invalid format.

Minimal reproducer (all files are empty):

$ find . -name \*.py
./foobar/__init__.py
./foobar/foo-bar.py
$ python3 -c 'import importlib; importlib.import_module("foobar.foo-bar")'
$ python3 -c 'import pkgutil; pkgutil.resolve_name("foobar.foo-bar")'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib/python3.10/pkgutil.py", line 687, in resolve_name
    raise ValueError(f'invalid format: {name!r}')
ValueError: invalid format: 'foobar.foo-bar'

I would expect those to be consistent in the format they accept, i.e. accept and reject the same inputs.
My current actual problem is that unittest.mock.patch uses pkgutil.resolve_name() in Python 3.11 (but not in Python 3.10), what means that one cannot easily patch a function inside a Django management command module that contains a dash.

Your environment

Tested on Debian testing amd64 (x86_64) as of today, with both python 3.11.1 and 3.9.10.

Reproduisez l’exemple avec foobar/foo-bar.py, puis examinez l’implémentation de resolve_name dans pkgutil.py ainsi que unittest.mock.patch là où il est utilisé. La modification est terminée lorsque les noms acceptés par importlib.import_module sont gérés de manière cohérente par le chemin de patch, avec une couverture pour un nom de fichier de module contenant un tiret.