Nginx – How to setup a different root for an Nginx location

I'm setting up my local web dev server using NGINX and PHP-FPM on OS X.
I've installed both services and set up a virtual for localhost domain. So far everything works:

• nginx is running correctly
• it's able to read files from the custom root configured for localhost server_name
• php files are processed correctly

The next thing that I'm trying to set up is an alias for the /phpmyadmin path on the localhost domain. I would like for the url http://localhost/phpmyadmin to load its contents from /usr/local/share/phpmyadmin rather than from the default configured root.

I've added this location block in my localhost server configuration:

location /phpmyadmin {
    alias    /usr/local/share/phpmyadmin;
    include   /usr/local/etc/nginx/conf.d/php-fpm;
}

but the response on http://localhost/phpmyadmin requests is 404.

Here are the configs that I used:

/usr/local/etc/nginx/nginx.conf

worker_processes  2;

error_log  /usr/local/etc/nginx/logs/error.log debug;

events {
    worker_connections  1024;
}

http {
    include             mime.types;
    default_type        application/octet-stream;

    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';

    access_log  /usr/local/etc/nginx/logs/access.log  main;

    sendfile            on;

    keepalive_timeout   600;

    gzip on;
    gzip_disable "msie6";

    gzip_vary on;
    gzip_proxied any;
    gzip_comp_level 2;
    gzip_buffers 16 8k;
    gzip_http_version 1.1;
    gzip_min_length 256;
    gzip_types text/plain text/css application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript application/vnd.ms-fontobject application/x-font-ttf font/opentype
image/svg+xml image/x-icon;

    index index.html index.php;

    include /usr/local/etc/nginx/sites-enabled/*;
}

/usr/local/etc/nginx/sites-available/default

server {
    listen       80;
    server_name  localhost;
    root       /Users/sebi/www/localhost;

    access_log  /usr/local/etc/nginx/logs/default.access.log  main;
    error_log  /usr/local/etc/nginx/logs/default.error.log debug;

    location / {
        include   /usr/local/etc/nginx/conf.d/php-fpm;
    }

    location /phpmyadmin {
        alias    /usr/local/share/phpmyadmin;
        include   /usr/local/etc/nginx/conf.d/php-fpm;
    }

    error_page  404     /404.html;
    error_page  403     /403.html;
}

/usr/local/etc/nginx/conf.d/php-fpm

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

* UPDATE *
I figured out that my location block for /phpmyadmin was misconfigured. I need to point it to /usr/local/share like this:

location /phpmyadmin {
    alias    /usr/local/share;
    include   /usr/local/etc/nginx/conf.d/php-fpm;
}

but this still doesn't work and I found out that it's due to how the path is configured. It's a relative symlink. If I create a new symlink to the absolute path, it will work.

Examples:

/usr/local/share/phpmyadmin -> ../Cellar/phpmyadmin/4.7.4/share/phpmyadmin doesn't work resulting in a directory index of "/usr/local/share/" is forbidden
error

/usr/local/share/pma -> /usr/local/Cellar/phpmyadmin/4.7.4/share/phpmyadmin works.

Any ideas on how to configure nginx to allow reading from relative symlinks?