It's in svn too. $path was introduced on 15623, by greg.
http://svn.wikimedia.org/viewvc/mediawiki/trunk/phase3/includes/templates/N…
What is your $_SERVER['SCRIPT_NAME'] ?
See if this change on /includes/templates/NoLocalSettings.php (line 12)
fixes it.
-$path = preg_replace('/index.php/', '',
$_SERVER['SCRIPT_NAME']);
+$path = preg_replace('/index.php/', '/',
$_SERVER['SCRIPT_NAME']);