'Override C{os.waitpid}. Return values meaning that the child process
has exited, save executed action.'

def waitpid(self, pid, options):

    self.actions.append('waitpid')
    if (self.raiseWaitPid is not None):
        raise self.raiseWaitPid
    if (self.waitChild is not None):
        return self.waitChild
    return (1, 0)
