Why is this nginx location section causing my php file to download?

Question

This is my basic configuration for a wordpress site.

server {
    root          /var/www/site;
    listen        *****;
    server_name   *****;
    include       basics.conf;
}

As soon as I add the location section to restrict the access to WP login, the wp-login.php file is send to the browser instead being executed as php. I have

server {
    root          /var/www/site;
    listen        *****;
    server_name   *****;
    include       basics.conf;

    location ^~ /wp-login.php {
        auth_basic            "Restricted Area";
        auth_basic_user_file  /etc/nginx/.htpasswd;
    }
}

I've tried copying what I have in my basics.conf after the auth_ settings but it didn't made it work either. My location / is also configured in my basics.conf because I use it for all php sites.

server {
    root          /var/www/site;
    listen        *****;
    server_name   *****;
    include       basics.conf;

    location ^~ /wp-login.php {
        auth_basic            "Restricted Area";
        auth_basic_user_file  /etc/nginx/.htpasswd;

        index index.html index.htm index.php;
        allow all;

        if (-f $request_filename) {
            break;
        }
        if (!-f $request_filename) {
            rewrite ^/(.+)$ /index.php last;
            break;
        }
    }
}

This is my basics.conf

location / {
    index index.html index.htm index.php;
    allow all;

    if (-f $request_filename) {
        break;
    }
    if (!-f $request_filename) {
        rewrite ^/(.+)$ /index.php last;
        break;
    }
}
include php-fastcgi.conf;

This is my php-fastcgi.conf

location ~ \.php$ {
    try_files  $uri =404;
    fastcgi_intercept_errors on;
    fastcgi_pass   127.0.0.1:9000;
    fastcgi_index  index.php;
    fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
    include        fastcgi_params;
}

So how can I get my login protected by auth while keep it being parsed as php instead of being send to the browser?