wordpress 2.9.2 query string question

I did some edit, no sure it is safe or not, please comment on this solution.
wp-includes\canonical.php
original:

// Note that you can use the “redirect_canonical” filter to cancel a canonical redirect for whatever reason by returning FALSE
$redirect_url = apply_filters(‘redirect_canonical’, $redirect_url, $requested_url);

if ( !$redirect_url || $redirect_url == $requested_url ) // yes, again — in case the filter aborted the request
return false;

line 293 I added

list($base_url, $query_string) = explode(‘?’,$requested_url);
$position = strpos($query_string, ‘&’);
if($redirect_url != $requested_url)
{
if($position == 0)
{
return false;
}
}

After I did the edit, I able to passing with ?& together without any problem.