anchor.diff:    postInstall = ''
       wrapProgram "$out/bin/vagrant" \
         --set GEM_PATH "${deps}/lib/ruby/gems/${ruby.version.libDir}" \
  -      --prefix PATH ':' "${lib.getBin libarchive}/bin" \
  -      ${lib.optionalString withLibvirt ''
  -        --prefix PATH ':' "${pkgconfig}/bin" \
  -        --prefix PKG_CONFIG_PATH ':' \
  -          "${lib.makeSearchPath "lib/pkgconfig" [ libvirt ]}"
  -      ''}
  +      --prefix PATH ':' "${lib.getBin libarchive}/bin"
   
       mkdir -p "$out/vagrant-plugins/plugins.d"
       echo '{}' > "$out/vagrant-plugins/plugins.json"
  
positive.code:   dontBuild = false;
    src = fetchurl { inherit url sha256; };
  
    buildInputs = lib.optional withLibvirt [ libvirt pkgconfig ];
  
    patches = [
      ./unofficial-installation-nowarn.patch
      ./use-system-bundler-version.patch
  
negative.code: { lib, fetchurl, buildRubyGem, bundlerEnv, ruby, libarchive, writeText, withLibvirt ? true}:
  
  let
    # NOTE: bumping the version and updating the hash is insufficient;
  