OS X and python 3.7.2

[stavinsky]

Daemon is not starting on this configuration. I understand that this python really old. I don't think this bug should be fixed. But I spend two days to understand what happens.

The problem is that on such configuration cluster can't start child processes and it waits forever in that loop

        while not self.start_event.is_set():
            sleep(0.1)

in the cluster.py file Hope this issue will save time for other people. after upgrade to python 3.9.2 everything works as expected.