Below is a much simplified version of what I have in the configuration file of a server run by Nginx 1.2.5, yet it causes 301 Moved Permanently with Location: http://example.com/phpmyadmin/ before serving data, which is not what I expected from the default behavior of the rewrite directive.

server {
    listen 80;
    location /pma {
        rewrite ^ /phpmyadmin;
    }
    location /phpmyadmin {
        root /var/www;
        index Documentation.html;
    }
}

When I follow http://example.com/pma, the data is served but the URL in the browser is changed to http://example.com/phpmyadmin/ while it was supposed to stay http://example.com/pma.

How do I avoid Nginx sending 301 Moved Permanently so that it doesn't expose the actual directory structure on my server?