An earlier change added support for versionless authurls, but the
huristic to detect them didn't work for some configurations I've
encountered.
Now we use a little bit tighter pattern matching and support auth_url
values with more than one path component.
Change-Id: I5a99c7b4e957ee7c8a5b5470477db49ab2ddba4b
Related-Change-Id: If7ecb67776cb77828f93ad8278cc5040015216b7