API redirecting to URL with a trailing slash if one is not included

Expected Behavior

The API returns a response

Current Behavior

The API sends back a 301 permanent redirect to the URL with a trailing slash at the end, which given the example below would be https://mit-open-rc.odl.mit.edu/api/v0/users/me/?format=json

Steps to Reproduce

1. Navigate to an API endpoint like https://mit-open-rc.odl.mit.edu/api/v0/users/me?format=json

Additional Details

This was discovered while testing https://github.com/mitodl/mit-open/pull/429/. The mit-open API implementation in OCW is entirely done from frontend Javascript, with fetch commands (at least for now). When performing a fetch using a site that has to be accessed with CORS, a redirect breaks the flow. Since 3xx responses are not part of the CORS spec, the response is returned sans CORS headers. Since the request is a CORS request to begin with and the Access-Control-Allow-Origin header is not returned by the server with the 301, the browser generates a CORS error and does not follow the redirect. In order for this strategy to work in OCW, the API URLs need to follow the exact schema the API needs, and / or the API needs to not redirect and enforce a trailing slash.

Start by tracing the API route handling for an endpoint such as /api/v0/users/me and review how requests without a trailing slash are handled. Reproduce the request with and without the slash, then verify that the chosen URL behavior avoids a redirect that prevents the CORS response from being used.