Partial specialization with custom post_generation for M2M

I may be missing something, but I am having trouble registering a "partial specialization" fixture for a factory with a ManyToMany field.

I tried using [the example in factoryboy docs][1], combined with the example in fixture attributes, but it throws TypeError: int() argument must be a string or a number, not 'LazyFixture'. Is this something we can even do?

Here's a test case:

class UserFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = models.User

    name = "John Doe"

    @factory.post_generation
    def groups(self, create, extracted, **kwargs):
        if not create:
            # Simple build, do nothing.
            return

        if extracted:
            # A list of groups were passed in, use them
            for group in extracted:
                self.groups.add(group)

register(UserFactory, "special_user", groups=[LazyFixture("group")])

Start with the supplied UserFactory test case and the fixture-attributes example linked in the issue. Trace how register handles groups=[LazyFixture("group")] alongside the custom post_generation method, then verify the TypeError no longer occurs and the partial specialization works as intended.