Corrected test docstring.

    @override_settings(AUTH_USER_MODEL='auth.CustomUser')

    def test_swappable_user_missing_required_field(self):

        "A superuser can be created when a custom User model is in use"

        "A Custom superuser won't be created when a required field isn't provided"

        # We can use the management command to create a superuser

        # We skip validation because the temporary substitution of the

        # swappable User model messes with validation.