For me this didn't work. I had to use request(options) and then renderRequest.on('response', ...) etc.
I see you already added support for gzip from prerender-node to the prerender server. However, if I'm correct you don't support requests to prerender-node with gzip yet. As you might know, search engines like google will do requests that accept encoding. So in that case you can just respond the contents from the prerender server and don't need to gunzip it in prerender-node. That is what my pull request is doing.

To be honest, I didn't realise there were tests so I didn't run them. I'll look into that now.