cookielib doesn't handle URLs like "http://server/script?
err=/base/error.html&ok=/base/ok.html", as 
CookieJar::_cookie_from_cookie_tuple uses rfind("/") to strip off the 
end of the URL, returning "http://server/script?
err=/base/error.html&okc=/base" instead of "http://server/script".

My suggested fix (attached, line 1465-1468) is to first strip off 
anything after "?" if present, then continue as with existing code.