pylint: make unsupported-assignment-operation check local
    
    unsupported-assignment-operation is useful at times, make it only
    local, not global.
    
    https://pagure.io/freeipa/issue/6874
    
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Florence Blanc-Renaud <frenaud@redhat.com>