'Patch C{_options.installReactor} so we can capture usage and prevent
actual installs.'

def patchInstallReactor(self):

    self.installedReactors = {}
    def installReactor(_, name):
        reactor = MemoryReactor()
        self.installedReactors[name] = reactor
        return reactor
    self.patch(TwistOptions, 'installReactor', installReactor)
