function baw_hack_cat( $wp )
{
    global $wp_query, $wp;
    if( $wp_query->query_vars['category_name'] != $wp_query->query['category_name'] ):
        wp_redirect( home_url( str_replace( $wp_query->query['category_name'], $wp_query->query_vars['category_name'], $wp->request ) ), 301 );
        die();
    endif;
}
add_action( 'wp', 'baw_hack_cat' );