Comment 3 for bug 1663920

npm has a super ugly way to work this around:
https://github.com/npm/npm/wiki/Troubleshooting#npm-only-uses-git-and-sshgit-urls-for-github-repos-breaking-proxies

We have no way to replace the global url in build.snapcraft.io before the pull, so this also seems to be a blocker for many nodejs snaps.