I'm writting a HTTP server and when i tried the Serendipity PHP Blog i get requests from the browser like this one:

GET /serendipity\_admin.php/templates/default/admin/pluginmanager.css HTTP/1.1

The "/serendipity\_admin.php" file does exist so the 
"/serendipity\_admin.php/templates/default/admin/pluginmanager.css" obviously must fail.

What should a webserver do when it discounters such a request?

I tried to just execute "/serendipity\_admin.php" with the usual HTTP request headers (REQUEST\_URI, PATH\_INFO etc), but this does not seem to work so there is some more magick required. Can someone please explain.