clear out any existing objects in the setup

Author: Mark Unsworth

tests/lookup/tests.py

@@ -18,6 +18,11 @@
 class LookupTests(TestCase):
 
     def setUp(self):
+
+        Author.objects.all().delete()
+        Article.objects.all().delete()
+        Tag.objects.all().delete()
+
         # Create a few Authors.
         self.au1 = Author(name='Author 1')
         self.au1.save()