Проглядел конфиг ещё раз, может быть, это всё из-за ssi?
Впрочем, вот он.

# nginx_new -V
nginx version: nginx/1.2.9
built by gcc 4.4.5 (Debian 4.4.5-8)
TLS SNI support enabled
configure arguments: --prefix=/ --sbin-path=/usr/sbin/nginx_new --conf-path=/etc/nginx_new/nginx_new.conf --pid-path=/var/run/nginx_new.pid --lock-path=/var/lock/nginx_new.lock --error-log-path=/var/log/nginx_new/error.log --http-log-path=/var/log/nginx_new/access.log --user=www-data --group=www-data --with-http_ssl_module --with-http_realip_module --with-http_gzip_static_module --with-http_image_filter_module --with-pcre=../../libs/pcre-8.31 --with-pcre-jit --with-zlib=../../libs/zlib-1.2.7 --with-openssl=../../libs/openssl-1.0.1c --http-client-body-temp-path=/var/lib/nginx_new/body --http-proxy-temp-path=/var/lib/nginx_new/proxy --http-fastcgi-temp-path=/var/lib/nginx_new/fastcgi --http-uwsgi-temp-path=/var/lib/nginx_new/uwsgi-temp --http-scgi-temp-path=/var/lib/nginx_new/scgi-temp --with-http_dav_module --with-http_stub_status_module --with-http_geoip_module --with-http_flv_module --with-http_mp4_module --add-module=../../libs/nginx_mogilefs_module-1.0.4 --add-module=../../libs/ngx_devel_kit-0.2.18 --with-http_secure_link_module --add-module=../../libs/lua-nginx-module-0.8.0 --add-module=../../libs/redis2-nginx-module-0.10 --add-module=../../libs/echo-nginx-module-0.45

#nginx.conf
user www-data;
worker_processes 8;

error_log /var/log/nginx_new/error.log;
pid /var/run/nginx_new.pid;

worker_priority -10;
worker_rlimit_nofile 250000;
worker_rlimit_sigpending 32768;

events {
worker_connections 10240;
use epoll;
}

http {
geoip_country /usr/share/GeoIP/GeoIP.dat;
geoip_city /usr/share/GeoIP/GeoLiteCity.dat;

include /etc/nginx_new/mime.types;
default_type application/octet-stream;

log_format main '$geoip_country_code $remote_addr - $remote_user [$time_local] '
'"$request" $request_time $status $body_bytes_sent '
'"$http_referer" "$http_user_agent" '
'"$http_cookie" $http_host';

access_log off;

server_tokens off;

client_max_body_size 20m;
client_header_timeout 30s;
client_body_timeout 30s;
send_timeout 30;

client_header_buffer_size 4k;
large_client_header_buffers 8 8k;

output_buffers 256 128k;
postpone_output 1460;

keepalive_timeout 10;

sendfile on;
tcp_nopush on;
tcp_nodelay on;
ssi on;
ssi_types text/xml application/x-javascript;

open_file_cache max=20000 inactive=80s;
open_file_cache_valid 20s;
open_file_cache_min_uses 8;
open_file_cache_errors on;

gzip on;
gzip_comp_level 4;
gzip_disable "MSIE [1-6]\.";
gzip_buffers 32 8k;
gzip_min_length 1024;
gzip_proxied expired no-cache no-store private auth;
gzip_types text/plain text/css text/xml text/javascript application/x-javascript application/xml application/xml+rss image/x-icon;

reset_timedout_connection on;
recursive_error_pages on;

map $hostname $numfront { ~(?<s>\d+$) $s; default 0; }
add_header X-Frontend $numfront;
proxy_read_timeout 60;
proxy_send_timeout 60;
proxy_redirect off;
proxy_set_header Host $host;
proxy_set_header X-Forwarded-For $remote_addr;
proxy_set_header X-Frontend $hostname;

proxy_temp_path /var/lib/nginx_new/proxy_temp 1 2;

root /var/www/nginx-default/;

include /etc/nginx_new/conf.d/*.conf;