when assign client cookiejar not attached

[poweroftrue]

Hi

I'm using goreq (with #131 fix) on app engine and I found when I assign http client cookiejar not attached
I'm using this as a workaround I don't know if there's a better way to implement it:
Do() func:

                 if r.Client == nil {
		// use a client with a cookie jar if necessary. We create a new client not
		// to modify the default one.
		if r.CookieJar != nil {
			r.Client = &http.Client{
				Transport: transport,
				Jar:       r.CookieJar,
			}
		} else {
			r.Client = &http.Client{
				Transport: transport,
			}
		}
	} else {
		if r.CookieJar != nil {
			r.Client.Jar = r.CookieJar
		}
	}