Code review comment for lp:~salgado/launchpad/bug-527985

When the user doesn't authorize the OpenID provider to send their
details to the RP, the user will end up at the +openid-callback page,
which has a login link.

Currently, the link will be something like /+openid-callback/+login,
which causes LP to believe the user wants to be sent to +openid-callback
once the login is completed, but that's obviously not true -- that was
just a page the user ended up at after a failed login. The fix here
will just drop the /+openid-callback bit from the login link, similarly
to what we already do for the +logout page.