'Restore whatever signal handler was present when setUp ran.'

def tearDown(self):

    installHandler((-1))
    signal.signal(signal.SIGCHLD, signal.SIG_DFL)
    if (self.signalModuleHandler is not None):
        signal.signal(signal.SIGCHLD, self.signalModuleHandler)
    elif (self.oldFD != (-1)):
        installHandler(self.oldFD)
