Code review comment for lp:~lamont/maas/bug-1567176

I don't like the random numbers used here, but I don't have a better idea at the moment. We might have to let it slide unless someone else can think of a better way to do it.

You should be able to use self.patch() to mock rather than replacing methods with your mock by hand. This will ensure that all the proper cleanup happens, even in exception cases.