create subfolder at top level of tarball from Github

create a package dir at top level of tarball from Github

Tarballs that npm can use, package contents should reside
in a subfolder inside the tarball (usually it is called package/).
npm strips one directory layer when installing the package
(an equivalent of tar x --strip-components=1 is run).

See https://docs.npmjs.com/cli/v7/commands/npm-install

internal.nix

@@ -74,7 +74,9 @@ rec {
  name
  { } ''
  set +x
- tar -C ${src} -czf $out ./
+ mkdir package
+ cp -R ${src}/. package
+ tar -czf $out package
  '';
 
  # Description: Turns a dependency with a from field of the format