phptemplate_user_list overwrite

I want to override user_list template (one, used for active/last
users block). So, in 4.7 template.tpl.php added:

function phptemplate_user_list($items, $title = NULL) {
 return _phptemplate_callback('user_list', array('items' => $items,
'title' => $title));
}

and placed user_list.tpl.php in theme directory. This one contains

print ('Hello world!');

for debugging.
The cache is clear, and themes are reloaded, but *no change* in
active/last user's block

Missing something, or it's just bug?

Thank you