anchor.diff:      if args.config != null then
         args.config
       else if builtins.getEnv "NIXPKGS_CONFIG" != "" then
  -      import (builtins.toPath (builtins.getEnv "NIXPKGS_CONFIG")) { inherit pkgs; }
  +      import (builtins.toPath (builtins.getEnv "NIXPKGS_CONFIG")) {
  +        inherit pkgs;
  +      }
       else
         let
           home = builtins.getEnv "HOME";
  
positive.code:     else
        import ../stdenv {
          allPackages = args': import ./all-packages.nix (args // args');
          inherit lib targetSystem hostSystem config;
        };
  
    ### BUILD SUPPORT
  
    attrSetToDir = arg: callPackage ../build-support/upstream-updater/attrset-to-dir.nix {
      theAttrSet = arg;
    };
  
    autoreconfHook = makeSetupHook
      { substitutions = { inherit (pkgs) autoconf automake gettext libtool; }; }
      ../build-support/setup-hooks/autoreconf.sh;
  
    ensureNewerSourcesHook = { year }: makeSetupHook {}
      (writeScript "ensure-newer-sources-hook.sh" ''
        postUnpackHooks+=(_ensureNewerSources)
        _ensureNewerSources() {
          '${pkgs.findutils}/bin/find' "$sourceRoot" \
            '!' -newermt '${year}-01-01' -exec touch -h -d '${year}-01-02' '{}' '+'
        }
      '');
  
    buildEnv = callPackage ../build-support/buildenv { }; # not actually a package
  
    #buildFHSEnv = callPackage ../build-support/build-fhs-chrootenv/env.nix { };
  
  
negative.code:   # can be obtained from `pkgs' or `pkgs.xorg' (i.e. `defaultScope').
    # Use `newScope' for sets of packages in `pkgs' (see e.g. `gnome'
    # below).
    callPackage = self_.newScope { };
  
    callPackages = lib.callPackagesWith defaultScope;
  
  