Override _after_postgeneration to force save in User factory (#4534)

* Override _after_postgeneration to force save

Saving in _after_postgeneration was automatic in Factory Boy versions below 4.0, but must be done explicitly in newer versions.

* Clean up formatting

{{cookiecutter.project_slug}}/{{cookiecutter.project_slug}}/users/tests/factories.py

@@ -29,6 +29,13 @@ class UserFactory(DjangoModelFactory):
         )
         self.set_password(password)
 
+    @classmethod
+    def _after_postgeneration(cls, instance, create, results=None):
+        """Save again the instance if creating and at least one hook ran."""
+        if create and results and not cls._meta.skip_postgeneration_save:
+            # Some post-generation hooks ran, and may have modified us.
+            instance.save()
+
     class Meta:
         model = get_user_model()
         django_get_or_create = ["{{cookiecutter.username_type}}"]