I could not figure out why try_files in a nested location defined with a regexp does not work in nginx/1.4.6 under Ubuntu 14.04. Consider the following config:

server {
listen 8080 default_server;
root /usr/share/nginx/html;
autoindex on;

location /x/ {
alias /test/;
location ~ ^/x/test {
try_files $uri =404;
}
}
}

With /test containing publically readable file test.html and directory test_dir this does not works as expected. While localhost:/x/ properly lists directory context of /test and localhost:/x/test_dir/ is reported as 404 not found , nginx also reported as 404 not found localhost:/x/test.html even if the file exists.

Now, if replace the regexp with a simple prefix so the location reads:

location /x/ {
alias /test/;
location /x/test {
try_files $uri =404;
}
}

then everything work. That is, both localhost:/x/ and localhost:/x/test.html are accessible and only localhost:/x/test_dir/ is 404 not found.

So what is wrong with the usage of try_files in the initial regexp-based location config?