That's a different issue. Based on the problem statement and hints provided, the fix is straightforward. The issue is that when `models.Model` is serialized in the `bases` tuple of a migration, it outputs `models.Model` but doesn't include the necessary import statement `from django.db import models`.

Here's the patch:

--- a/django/db/migrations/serializer.py
+++ b/django/db/migrations/serializer.py
@@ -273,7 +273,7 @@ class TypeSerializer(BaseSerializer):
 class TypeSerializer(BaseSerializer):
     def serialize(self):
         special_cases = [
-            (models.Model, "models.Model", []),
+            (models.Model, "models.Model", ['from django.db import models']),
             (type(None), 'type(None)', []),
         ]
         for case, string, imports in special_cases: