'If a CGI script emits two instances of the same header, both are sent
in the response.'

def test_duplicateHeaderCGI(self):

    cgiFilename = self.writeCGI(DUAL_HEADER_CGI)
    portnum = self.startServer(cgiFilename)
    url = ('http://localhost:%d/cgi' % (portnum,))
    url = url.encode('ascii')
    agent = client.Agent(reactor)
    d = agent.request('GET', url)
    d.addCallback(discardBody)
    def checkResponse(response):
        self.assertEqual(response.headers.getRawHeaders('header'), ['spam', 'eggs'])
    d.addCallback(checkResponse)
    return d
