MIME type oddity when using try_files in combination with location/alias using regex captures

[Christoph Schug]

Hello!

Given is following minimized test case

server {
     listen                          80;
     server_name                     t1.example.com;

     root                            /data/web/t1.example.com/htdoc;

     location                        ~ ^/quux(/.*)?$ {
         alias                       /data/web/t1.example.com/htdoc$1;
         try_files                   '' =404;
     }
}

on Nginx 1.3.4 (but not specific to that version)

# nginx -V
nginx version: nginx/1.3.4
TLS SNI support enabled
configure arguments: --prefix=/usr/share/nginx 
--conf-path=/etc/nginx/nginx.conf --sbin-path=/usr/sbin/nginx 
--http-log-path=/var/log/nginx/access.log 
--error-log-path=/var/log/nginx/error.log --pid-path=/var/run/nginx.pid 
--user=nginx --group=nginx --with-openssl=openssl-1.0.1c --with-debug 
--with-http_stub_status_module --with-http_ssl_module --with-ipv6

and following file system layout

# find /data/web/t1.example.com/htdoc/
/data/web/t1.example.com/htdoc/
/data/web/t1.example.com/htdoc/foo
/data/web/t1.example.com/htdoc/foo/bar.gif

Accessing the file directly returns the expected 'Content-Type' 
response header with the value 'image/gif'

$ curl -s -o /dev/null -D - -H 'Host: t1.example.com' 
http://127.0.0.1/foo/bar.gif
HTTP/1.1 200 OK
Server: nginx/1.3.4
Date: Thu, 02 Aug 2012 05:13:40 GMT
Content-Type: image/gif
Content-Length: 68
Last-Modified: Thu, 02 Aug 2012 05:04:56 GMT
Connection: keep-alive
ETag: "501a0a78-44"
Accept-Ranges: bytes

Accessing the file via location /quux returns 'Content-Type' response 
header with the value 'application/octet-stream' (basically it falls 
back to the setting of 'default_type')

$ curl -s -o /dev/null -D - -H 'Host: t1.example.com' 
http://127.0.0.1/quux/foo/bar.gif
HTTP/1.1 200 OK
Server: nginx/1.3.4
Date: Thu, 02 Aug 2012 05:13:42 GMT
Content-Type: application/octet-stream
Content-Length: 68
Last-Modified: Thu, 02 Aug 2012 05:04:56 GMT
Connection: keep-alive
ETag: "501a0a78-44"
Accept-Ranges: bytes

It is unclear to me if this is expected behavior (and if so, I am 
having a hard time to find it in the documentation) and what would be 
the best way to mitigate the problem. Defining nested locations within 
the /quux one for each combination of file extension/MIME type works but 
looks very wrong to me.

-cs