It seems to be it doesn't work because http:// isn't being specified in the url. If it has
http://www.google.com passed to it for example it will work but if just
www.google.com it will not redirect. If you specify a URL to redirect to yourself you can fix this, if you just want it to redirect users it depends if they type http:// or not and they likely won't.
Just what I've seemed to experience from trial and error redirecting after auth..