Added tests for accessing nullable ForeignKey after saving and fetching from the database (refs #8093).

git-svn-id: http://code.djangoproject.com/svn/django/trunk@8198 bcc190cf-cafb-0310-a4f2-bffc1f526a37

tests/regressiontests/many_to_one_regress/models.py

@@ -84,6 +84,16 @@ True
 >>> p.bestchild is None
 True
 
+# bestchild should still be None after saving.
+>>> p.save()
+>>> p.bestchild is None
+True
+
+# bestchild should still be None after fetching the object again.
+>>> p = Parent.objects.get(name="Parent")
+>>> p.bestchild is None
+True
+
 # Assigning None fails: Child.parent is null=False.
 >>> c.parent = None
 Traceback (most recent call last):