Add game rule that can keep going after rolling a 6

[munichpavel]

Having a while roll_value == 6 kills my client unit tests of Client.take_turn(), as they run for ever with my monkeypatched roll value of 6 in one test.

The type of situation I would like is that the dice roll returns a 6, but then a 1. I will have to change my test in any case ... like here:
https://stackoverflow.com/questions/24897145/python-mock-multiple-return-values?noredirect=1&lq=1

Yup, that's it in accepted answer, use an iterable with Mock.