npm install network errors with build.snapcraft.io proxy configuration

Note: I originally discovered this issue last year and it got fixed upstream with electron-packager (https://forum.snapcraft.io/t/getaddrinfo-enotfound-github-com-builds-failing-on-snapcraft-io-due-to-network-problems/14164/6) but the problem seems to have returned.

My snapcraft.yaml (https://github.com/krellian/kiosk/blob/master/snap/snapcraft.yaml) runs `npm install` in override-build, which includes installing the electron-packager npm package. That installation process tries to fetch resources from github.com:443 and fails due to the network proxy configuration being used on build.snapcraft.io

        RequestError: getaddrinfo ENOTFOUND github.com github.com:443

Full build log here: https://build.snapcraft.io/user/krellian/kiosk/1034152

I was able to work around this issue by adding the following to my snapcraft.yaml but it would be great if this could be fixed. I suspect it's probably an upstream bug again, but perhaps there's something that could be changed about the build server configuration to reduce these types of errors?

        if [ -n "$http_proxy" ]; then
          export ELECTRON_GET_USE_PROXY=1
          export GLOBAL_AGENT_HTTP_PROXY="${http_proxy}"
          export GLOBAL_AGENT_HTTPS_PROXY="${http_proxy}"
        fi