anchor.diff:      in
         # allow both:
         # { /* the config */ } and
  -      # { pkgsOrig, pkgs, ... } : { /* the config */ }
  +      # { pkgs, ... } : { /* the config */ }
         if builtins.isFunction configExpr
  -        then configExpr { inherit pkgs pkgsOrig; }
  +        then configExpr { inherit pkgs; }
           else configExpr;
   
     # Return an attribute from the Nixpkgs configuration file, or
  
positive.code:   python24 = lowPrio (callPackage ../development/interpreters/python/2.4 { });
  
    python26Base = lowPrio (makeOverridable (import ../development/interpreters/python/2.6) {
      inherit fetchurl stdenv zlib bzip2 gdbm;
      arch = if stdenv.isDarwin then darwinArchUtility else null;
      sw_vers = if stdenv.isDarwin then darwinSwVersUtility else null;
    });
  
negative.code:   # Allow packages to be overriden globally via the `packageOverrides'
    # configuration option, which must be a function that takes `pkgs'
    # as an argument and returns a set of new or overriden packages.
    # The `packageOverrides' function is called with the *original*
    # (un-overriden) set of packages, allowing packageOverrides
    # attributes to refer to the original attributes (e.g. "foo =
    # ... pkgs.foo ...").
    pkgs = applyGlobalOverrides (getConfig ["packageOverrides"] (pkgs: {}));
  
  
    # Return the complete set of packages, after applying the overrides
    # returned by the `overrider' function (see above).
    applyGlobalOverrides = overrider:
      let
        # Call the overrider function.  We don't want stdenv overrides
        # in the case of cross-building, or otherwise the basic
        # overrided packages will not be built with the crossStdenv
        # adapter.
        overrides = overrider pkgsOrig //
          (lib.optionalAttrs (pkgsOrig.stdenv ? overrides && crossSystem == null) pkgsOrig.stdenv.overrides);
  
        # The un-overriden packages, passed to `overrider'.
        pkgsOrig = pkgsFun pkgs {}; 
  
        # The overriden, final packages.
        pkgs = pkgsFun pkgs overrides; 
      in pkgs;
  
  
    # The package compositions.  Yes, this isn't properly indented.
    pkgsFun = pkgs: __overrides:
      with helperFunctions;
      let defaultScope = pkgs // pkgs.xorg; in
      helperFunctions // rec {
  
    # `__overrides' is a magic attribute that causes the attributes in
    # its value to be added to the surrounding `rec'.  We'll remove this
    # eventually.
    inherit __overrides;
  
  
    # We use `callPackage' to be able to omit function arguments that
  