cache.json not available from server in local environment

[flyinggrizzly]

In a local server (e.g localhost:8080), the cache.json file does not appear to be served by Neuron/rib. It is generated and present (and accessible in a site hosted from S3), but not accessible from the browser when served locally.

Neuron version: 1.9.19.0
OS:
server: WSL2 running Ubuntu 20.04
browser: Firefox on Windows 10

This is a change in behavior--I've been using cache.json on Neuron v. 1.9.3.0 in a custom browser script, but it no longer works after updating.

The browser script isn't important, but this will make work on #568 difficult if there isn't a cache file to work with to build the search index.

If this is an intentional change, feel free to close--I'll figure out a way to work with localfiles instead of the rib dev server for #568.

[srid]

Fixed in 1.9.20.0. This was a regression introduced in #564