fixes missing host header on retried request when using forever agent
i'm trying to remember why this line is there in the first place. can anyone think of a reason we need to cleanup the host header on error. once we hit an error (if we aren't using forever agent) there wont be additional requests?
If there was a reason to have it, we can always just move it below the forever agent condition instead of removing it. However, when a request errors out and the forever agent isn't being used, an error is just returned to the callback, so is it really necessary to modify anything on the request object?