How to set up wordpress in subdir with php-fpm on unix socket?

I want to migrate my wordpress installation from apache to nginx. Actually everything is working (at least it seems so) but the rewriting of urls.

My setup:

• php-fpm on unix instead tcp socket
• wordpress installation in /var/www/blog/
• ubuntu 12.04 lts
• nginx 1.1.19

Following the nginx documentation for wordpress I tried to add

location /blog {
        try_files $uri $uri/ /wordpress/index.php?$args;
}

location ~ .php$ {
        # ...
        fastcgi_split_path_info ^(/blog)(/.*)$;
}

But this is still not working for me. Do you have any ideas?

# /etc/nginx/sites-enabled/default
server {
listen 80;

root /var/www/blog;
index index.php;

server_name 12.34.56.789; # server isn't connected with a domain for now

location = /favicon.ico { log_not_found off; access_log off; }

location = /robots.txt { allow all; log_not_found off; access_log off; }

location ~ /. { deny all; }

location ~* /(?:uploads|files)/.*.php$ { deny all; }

location /blog {
        try_files $uri $uri/ /blog/index.php?$args;
}

location ~ .php$ {
    fastcgi_split_path_info ^(/blog)(/.*)$;
    try_files $uri =404;
    fastcgi_pass unix:/var/run/php5-fpm.sock;
    fastcgi_index index.php;
    include fastcgi_params;
}
}

also changed www.conf

# /etc/php5/fpm/pool.d/www.conf
# ...
listen = /var/run/php5-fpm.sock
# ...

php.ini changed cgi.fix_pathinfo

# /etc/php5/fpm/php.ini
# php.ini
# ...
cgi.fix_pathinfo=0
# ...