blocks/online_users/block_online_users.php - line:119

This SQL query would always return 1 (number of instances the first userid in the returned SQL)

$usercount = count_records_sql("SELECT COUNT(u.id), u.id $from $where GROUP BY u.id");

The patch counts the distinct userids to correctly return the real userc ount. :-

$usercount = count_records_sql("SELECT COUNT(DISTINCT(u.id)) $from $where");