nginx routing with django

Question

I'm a bit stuck on how to accomplish the setup I want. Putting aside whether it's a good idea, I am trying to setup a development/test and production django application on the same server under the same domain. I am using nginx as the public-facing server, which then should send requests to the appropriate application server based on whether the url starts with the /dev/ prefix. However, I cannot get the nginx configuration quite right.

Ideally, requests to http://example.com/admin go to the production app, and http://example.com/dev/admin goes to the dev version. This way, the django urls.py is the same for both, such as:

urlpatterns = [
    path('admin/', admin.site.urls),
    ... other paths ...
]

The django apps are in docker containers, which communicate with the host machine via unix sockets. That is, I start the docker container with something like:

docker run -v /www:/host_dir me/mydocker

and in that container, the entrypoint command is:

gunicorn myapp.wsgi:application --bind=unix:/host_dir/xyz.sock

My nginx conf on the host machine looks like:

server {
    listen 80;
    listen [::]:80;
    server_name 35.231.70.176;

    location /dev {
        include proxy_params;
        proxy_pass http://unix:/www/dev.sock:;
    }

    location / {
        include proxy_params;
        proxy_pass http://unix:/www/production.sock:;
    }
}

In this configuration, I get the following:

http://example.com/admin works as expected

http://example.com/dev/admin goes to the PRODUCTION admin site.

In addition to the location block above, I have tried several variants in the nginx conf (keeping the location / {...} block the same as above), including:

1. Add slash to location:

   location /dev/ {
       include proxy_params;
       proxy_pass http://unix:/www/dev.sock:;
   } 
   

2. Add slash to proxy_pass:

   location /dev {
       include proxy_params;
       proxy_pass http://unix:/www/dev.sock:/;
   } 
   

3. Add slash to both location and proxy pass:

   location /dev/ {
       include proxy_params;
       proxy_pass http://unix:/www/dev.sock:/;
   } 
   

ALL of these variants end up sending http://example.com/dev/admin to the production application, so I'm confused. I thought that since it first matches the /dev block, it should send the request to the dev application, but clearly I'm not understanding.