Attempt to adopt the proposed unit test

refs #5562


git-svn-id: svn://svn.twistedmatrix.com/svn/Twisted/branches/iocp-5562@36282 bbbe8e31-12d6-0310-92fd-ac37d47ddeeb
Apply hopefully more reliable version from BrianMatthews

git-svn-id: svn://svn.twistedmatrix.com/svn/Twisted/branches/iocp-5562@36724 bbbe8e31-12d6-0310-92fd-ac37d47ddeeb