log with email

I just need to make possible login with nickname OR email, I've tried modify this rows on login.php (42-45)

    if (in_array($db_type, array('mysql', 'mysqli', 'mysql_innodb', 'mysqli_innodb')))
        $query['WHERE'] = 'username=\''.$forum_db->escape($form_username).'\' or username=\''.$forum_db->escape($form_email).'\'';
    else
        $query['WHERE'] = 'LOWER(username)=LOWER(\''.$forum_db->escape($form_username).'\') or LOWER(username)=LOWER(\''.$forum_db->escape($form_username).'\')';

but it dont work, someone can help me in make this change?

Thanks in adavnced
Luca