This code:
    def _watch_mock(self, good_exit, bad_exit):
        (aux_pid, status) = os.waitpid(self._childpid, os.WNOHANG)
        status = os.WEXITSTATUS(status)
        if aux_pid:
            self._log("_watch_mock(): PID %d exit status %d\n" % (self._childpid, status))
            self._childpid = 0
            if status == 0:
                self._done_status = good_exit
                self._log("Setting Status Good! - %s\n" % self._done_status)
            elif status > 0:
                self._done_status = bad_exit
                self._log("Setting Status Bad! - %s\n" % self._done_status)

            self._copy_mock_output_to_log()
            self._start_cleanup()

Produced this output:

_watch_mock(): PID 24626 exit status 0
Setting Status Good! - failed