'Ensure non-existent SHA in wants are not tolerated'

def test_bogus_wants_failure(self):

    bogus_sha = self.cmt(2).id[::(-1)]
    haves = [self.cmt(1).id]
    wants = [self.cmt(3).id, bogus_sha]
    self.assertRaises(KeyError, self.store.find_missing_objects, haves, wants)
