Prevents a reference to the callback function being added to the original options object.
I discovered this by making a request with a callback, then reusing the options object I made the request with to make a streaming request, which called the callback a second time.
Copy options before adding callback.
this doesn't merge cleanly, please reopen when it does.
Merge branch 'master' of github.com:mikeal/request
Seemed to merge cleanly with master, what can I do to help?