Fix redirect from publiclist to mirrormanager.
    
    There have been reports that the old links pointing to the mirrorlist
    are no longer working:
    
     $ curl -I http://mirrors.fedoraproject.org/publiclist/
     Location: https://admin.fedoraproject.org/mirrormanager///
    
    This redirect still works but trying to access a specific mirrorlist
    fails:
    
     $ curl -I http://mirrors.fedoraproject.org/publiclist/EPEL/7/
     Location: https://admin.fedoraproject.org/mirrormanager///EPEL/7/
     $ curl -I https://admin.fedoraproject.org/mirrormanager///EPEL/7/
     HTTP/1.1 404 NOT FOUND
    
    At different places there are just too many slashes added. Removing the
    slashes seems to help.