Try to get the image [[Datei:File.jpg|thumb|300px]] through img_auth.php: http://localhost/mediawiki-1.17/img_auth.php/thumb/4/42/File.jpg/300px-File.jpg
r89627 works.
r89628 doesn't work:
<h1>Forbidden</h1><p>Invalid file extension found in the path info or query string.</p>
LocalSettings.php:
$wgScriptPath = "/mediawiki-1.17";
$wgUploadPath = "$wgScriptPath/img_auth.php";
Version: 1.17.x
Severity: normal