Can nginx set 'Origin' header when proxing websocket?

We know nginx can proxy WebSocket since version 1.3.13, and we also know some times WebSocket server will valid the 'Origin' header, so someone said you can do something like:

proxy_set_header Origin "";

render the origin header to null, but I test it using my Wheezy box(nginx-extras package in backports), and there is a negative result, server side still get the Origin header from client side.

So here is the question: that line does not work, right?