'Passing in None into timeout results in a value that is cached forever'

def test_zero_timeout(self):

    self.cache.set(u'key1', u'eggs', 0)
    self.assertEqual(self.cache.get(u'key1'), None)
    self.cache.add(u'key2', u'ham', 0)
    self.assertEqual(self.cache.get(u'key2'), None)
    self.cache.set_many({u'key3': u'sausage', u'key4': u'lobster    bisque'}, 0)
    self.assertEqual(self.cache.get(u'key3'), None)
    self.assertEqual(self.cache.get(u'key4'), None)
