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.

attached is a patch with the suggested fix along with a unit test.

The patch and tests look fine to me, Gregory. I verified it against the
trunk. Should not we have it for py3k as well?

yep it applies to all releases.  anyways, it won't make 2.6/3.0 but it
can be put into 2.5.3/2.6.1/3.0.1.

Do we have an RFC 3986 URI parser in the stdlib now?  It would be better
to use that if so, but I don't see one.  Failing that, an implementation
of the relevant part of that RFC is only about four lines of code, so
that would be better than naively looking for "?" (request_path should
probably be changed at the same time).

I'll try and add a patch that does that and check what Firefox does to
see if I agree it's a bug.

John, issue3647 tries relative url parsing and joins to be RFC3986
compliance.