slash in YOURLS charset

Plugin:

<?php

/*
Plugin Name: 00 TEST SLASH
Plugin URI:
Description:
Version: 1.0
Author: Ozh
Author URI: http://ozh.org/
*/

yourls_add_filter( 'get_shorturl_charset', 'ozh_slash_in_charset' );
function ozh_slash_in_charset( $in ) {
    return $in.'/';
}

?>

Test file :

<?php

var_dump( yourls_sanitize_keyword( 'omg/ozh;' ) );
// string 'omg/ozh' (length=7)

?>