Cloudflare WARP SSL issues

Reproduce the failure with dev or pkgx on macOS behind Cloudflare WARP, then inspect the fetch path in deno.land/x/libpkgx@v0.19.1/src/hooks/useDownload.ts and the callers in useSync.ts. Done means downloads work without manually installing the WARP certificate locally, with the supported certificate configuration documented or verified by a test.

We are running behind Cloudflare warp. Its a real pain that we have to install their certificates locally for things to work.
Running either dev or pkgx (latest versions on Mac) produced the following error:

× unexpected error client error (Connect)
│ TypeError: client error (Connect)
│     at async mainFetch (ext:deno_fetch/26_fetch.js:170:12)
│     at async fetch (ext:deno_fetch/26_fetch.js:391:7)
│     at async the_meat (https://deno.land/x/libpkgx@v0.19.1/src/hooks/useDownload.ts:96:15)
│     at async Object.download (https://deno.land/x/libpkgx@v0.19.1/src/hooks/useDownload.ts:25:25)
│     at async Object.sync (https://deno.land/x/libpkgx@v0.19.1/src/hooks/useSync.ts:57:5)
│     at async default (https://deno.land/x/libpkgx@v0.19.1/src/hooks/useSync.ts:15:5)
│     at async ensure_pantry (file:///var/folders/xq/vgsymdvs5dz687mdx4sq74_c0000gp/T/deno-compile-pkgx/pkgx/src/app.ts:160:5)
│     at async default (file:///var/folders/xq/vgsymdvs5dz687mdx4sq74_c0000gp/T/deno-compile-pkgx/pkgx/src/app.ts:129:9)
│     at async file:///var/folders/xq/vgsymdvs5dz687mdx4sq74_c0000gp/T/deno-compile-pkgx/pkgx/entrypoint.ts:59:3

Anyway to attach the cert required?