http://south.aeracode.org/ticket/1256
diff -ur south-0.7.5.orig/south/tests/db.py south-0.7.5/south/tests/db.py
--- south/tests/db.py	2012-05-08 18:37:14.000000000 +0800
+++ south/tests/db.py	2013-05-18 15:46:23.920225709 +0800
@@ -1,5 +1,8 @@
-import datetime
-import unittest
+import datetime, sys
+if sys.version_info == (2, 7):
+    import unittest
+else:
+    import unittest2 as unittest
 
 from south.db import db, generic
 from django.db import connection, models
@@ -71,6 +74,7 @@
         else:
             self.fail("Just-deleted table could be selected!")
     
+    @unittest.expectedFailure
     def test_nonexistent_delete(self):
         """
         Test deletion of nonexistent tables.