=== modified file 'tests/modeltests/force_insert_update/models.py'
--- tests/modeltests/force_insert_update/models.py	2008-08-20 18:50:06 +0000
+++ tests/modeltests/force_insert_update/models.py	2010-07-02 14:09:07 +0000
@@ -3,15 +3,38 @@
 automatic behaviour).
 """
 from django.db import models, transaction, IntegrityError
+from django.test import TestCase
 
 class Counter(models.Model):
-    name = models.CharField(max_length = 10)
+    name = models.CharField(max_length=10)
     value = models.IntegerField()
 
+class ProxyCounter(Counter):
+    class Meta:
+        proxy = True
+
+class SubCounter(Counter):
+    pass
+
 class WithCustomPK(models.Model):
     name = models.IntegerField(primary_key=True)
     value = models.IntegerField()
 
+class InheritanceTests(TestCase):
+    def test_force_update_on_proxy_model(self):
+        a = ProxyCounter(name="count", value=1)
+        a.save()
+        a.save(force_update=True)
+
+    def test_force_update_on_inherited_model_without_fields(self):
+        '''
+        Issue 13864: force_update fails on subclassed models, if they don't
+        specify custom fields.
+        '''
+        a = SubCounter(name="count", value=1)
+        a.save()
+        a.save(force_update=True)
+
 __test__ = {"API_TESTS": """
 >>> c = Counter.objects.create(name="one", value=1)