Twisted plugin needs to fail fast of port is taken

Question

I have a twistd plugin that listens on a port and does very simple things. The problem is that when I start it, if the post is not available it just sits there with the process running, but doing nothing. I need the process to exit immediately in this case so the larger system can notice and deal with the problem

I have code like this:

def makeService(options):
    root = Resource() #  Not what I actually have...
    factory = server.Site(root)
    server_string = b'tcp:{0}:interface={1}'.format(options['port'], options['interface'])
    endpoint = endpoints.serverFromString(reactor, server_string)
    service = internet.StreamServerEndpointService(endpoint, factory)
    return service

This results in:

2016-12-19T11:42:21-0600] [info] [3082] [-] Log opened.
[2016-12-19T11:42:21-0600] [info] [3082] [-] twistd 15.5.0 (/home/matthew/code-venvs/wgcbap/bin/python 2.7.6) starting up.
[2016-12-19T11:42:21-0600] [info] [3082] [-] reactor class: twisted.internet.epollreactor.EPollReactor.
[2016-12-19T11:42:21-0600] [critical] [3082] [-] Unhandled Error
        Traceback (most recent call last):
          File "/home/matthew/code-venvs/wgcbap/local/lib/python2.7/site-packages/twisted/scripts/_twistd_unix.py", line 394, in startApplication
            service.IService(application).privilegedStartService()
          File "/home/matthew/code-venvs/wgcbap/local/lib/python2.7/site-packages/twisted/application/service.py", line 278, in privilegedStartService
            service.privilegedStartService()
          File "/home/matthew/code-venvs/wgcbap/local/lib/python2.7/site-packages/twisted/application/internet.py", line 352, in privilegedStartService
            self._waitingForPort = self.endpoint.listen(self.factory)
          File "/home/matthew/code-venvs/wgcbap/local/lib/python2.7/site-packages/twisted/internet/endpoints.py", line 457, in listen
            interface=self._interface)
        --- <exception caught here> ---
          File "/home/matthew/code-venvs/wgcbap/local/lib/python2.7/site-packages/twisted/internet/defer.py", line 121, in execute
            result = callable(*args, **kw)
          File "/home/matthew/code-venvs/wgcbap/local/lib/python2.7/site-packages/twisted/internet/posixbase.py", line 478, in listenTCP
            p.startListening()
          File "/home/matthew/code-venvs/wgcbap/local/lib/python2.7/site-packages/twisted/internet/tcp.py", line 984, in startListening
            raise CannotListenError(self.interface, self.port, le)
        twisted.internet.error.CannotListenError: Couldn't listen on 127.0.0.1:9999: [Errno 98] Address already in use.

And it continues to run, doing nothing....

Adding a line service._raiseSynchronously = True just above the return works, but seems to be undocumented and feels dirty.

Is there an approved way to do this?