Fixed #18083 -- Fixed cascade deletion with proxy model of concrete subclass. Thanks Simon Charette for report and patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17887 bcc190cf-cafb-0310-a4f2-bffc1f526a37

tests/modeltests/proxy_model_inheritance/models.py

@@ -0,0 +1,13 @@
+
+from django.db import models
+
+
+class ConcreteModel(models.Model):
+    pass
+
+class ConcreteModelSubclass(ConcreteModel):
+    pass
+
+class ConcreteModelSubclassProxy(ConcreteModelSubclass):
+    class Meta:
+        proxy = True