POST not working on node 0.11.12

I'm getting this error on node 0.11.12 (latest unstable with harmony generators)

    _http_outgoing.js:341
        this._removedHeader[key] = false;
                                 ^
    TypeError: Cannot set property 'content-length' of undefined

my code is following:

    var nock = require("nock");
    var agent = require("thunkagent");
    
    var google = nock("http://google.com")
            .post("/post")
	    .reply(204);

    var request = agent
	    .post("http://google.com/post")
	    .send({a: 1})
	    .end();