nginx + wordpress in subfolder + debian configuration - php

Question

In a subfolder on a domain I want to install a wordpress blog. I use nginx. The URL to access the blog should be like this: example.com/blog
site config looks as follows:
server {
listen 80;
listen [::]:80;
root /var/www/example.com/html;
index index.php index.html index.htm index.nginx-debian.html;
server_name example.com www.example.com;
location /blog {
alias /var/www/example.comblog/html;
index index.php;
try_files $uri $uri/ /blog/index.php?q=$uri&$args;
}
location ~ /blog/.+\.php$ {
try_files $uri =404;
fastcgi_split_path_info ^(.+\.php)(/.+)$;
fastcgi_pass unix:/var/run/php5-fpm.sock;
fastcgi_index index.php;
include fastcgi_params;
}
location ~ /\.ht {
deny all;
}
}
The wordpress files reside in the folder
/var/www/example.comblog/html. When accessing example.com/blog,
the browser shows a 404 error.
In /etc/php5/fpm/php.ini I adapted this: cgi.fix_pathinfo=0
nginx version: nginx/1.6.2
/var/log/nginx/error.log does not show anything of interest
UPDATE 1:
After setting error logging to debug, (among others) the following lines appear. Maybe this helps:
open index "/var/www/example.comblog/html/index.php"
internal redirect: "/blog/index.php?"
rewrite phase: 1
test location: "/blog"
test location: ~ "/blog/.+\.php$"
using configuration "/blog/.+\.php$"
http script var: "/blog/index.php"
trying to use file: "/blog/index.php" "/var/www/example.com/html/blog/index.php"
The internal redirect seems incorrect? And in the last line there should be /var/www/example.comblog/html/blog/index.php instead of /var/www/example.com/html/blog/index.php. I suspect this is the reason for the 404. Because the index.php does not exist at /var/www/example.com/html/blog/index.php.
Update 2:
Okay there seems to be a long standing issue with using alias together with try_files.