> - try_files $uri $uri/ /foo/index.php?u=$irequest_uri;
> + try_files $uri $uri/ /foo/index.php?u=$request_uri;

This doesn't work. With q or u variables. I tried it on an installation of
Drupal with clean url. The request failed during an AJAX request.

index.php?q=$uri&$args works though.

Notice it's 'q=' not 'u='

-Hendry