Lighttpd

setup a fastcgi app which returns the following headers

X-Rewrite-URI: /backend.html
X-Rewrite-Host: 127.0.0.2

Have the following config lines in with lighty svn rev r1510

server.document-root        = "/usr/local/site/docroot/" 
server.modules  += ( "mod_proxy_backend_fastcgi" )
$HTTP["url"] =~ "\.php$" {
 proxy-core.balancer = "round-robin" 
 proxy-core.protocol = "fastcgi" 
 proxy-core.allow-x-rewrite = "enable" 
 proxy-core.backends = ( "127.0.0.1:9090" )
 proxy-core.max-pool-size = 16
}

server.modules  += ( "mod_proxy_backend_http" )
$HTTP["host"] =~ "127.0.0.2" {
   proxy-core.balancer = "sqf" 
   proxy-core.protocol = "http" 
   proxy-core.backends = ( "127.0.0.1:80" )
}

nginx is serving on 127.0.0.1:80

however strace shows that lighty is trying to stat the file
/usr/local/site/docroot/backend.html instead of internally going to
127.0.0.2 which then goes to 127.0.0.1

sent email to jakabosky who wrote back

"Also right now one proxy-core can't redirect internally to the other
proxy-core. The problem is that the plugin_data object is not cleared/reset,
so that the next proxy-core can be setup. It shouldn't be to hard to fix
this. Open a ticket about this problem"