These tests aren't guaranteed.  In case of ties, _make_leaderboard()'s ordering of the two ranks depends on the order returned from the db.  That is undefined.  Maybe this test should be:

# py2.7
self.assertIn(person2.rank, (2, 3))
self.assertIn(person3.rank, (2, 3))
self.assertNotEqual(person2.rank, person3.rank)

#py2.6 with nose
ok_(person2.rank in (2, 3))
ok_(person3.rank in (2, 3))
self.assertNotEqual(person2.rank, person3.rank)