When I set fastcgi_param in server context it is not set, if in location
it is set.
Wiki says it should work in http, server, location context.

server {
listen 80;
server_name .landingpage.dev;
access_log off;
error_log /var/log/nginx/landingpage.log;

root /vhosts/landingpage/public;
charset utf-8;

fastcgi_index index.php;
fastcgi_param SITE my_site;

location / {
try_files $uri $uri/ @fallback;
fastcgi_pass unix:/var/run/spawn-fcgi.sock;
fastcgi_param SCRIPT_FILENAME $document_root/$fastcgi_script_name;
#fastcgi_param SITE my_site;
include fastcgi_params;
}

location @fallback {
fastcgi_pass unix:/var/run/spawn-fcgi.sock;
fastcgi_param SCRIPT_FILENAME $document_root/index.php;
#fastcgi_param SITE my_site;
include fastcgi_params;
}
}