anchor.diff:    # (un-overriden) set of packages, allowing packageOverrides
     # attributes to refer to the original attributes (e.g. "foo =
     # ... pkgs.foo ...").
  -  pkgs = applyGlobalOverrides (self: config.packageOverrides or (super: {}));
  +  pkgs = pkgsWithOverrides (self: config.packageOverrides or (super: {}));
   
     # stdenvOverrides is used to avoid circular dependencies for building the
     # standard build environment. This mechanism use the override mechanism to
  
positive.code:   #
    # The result is `pkgs' where all the derivations depending on `foo'
    # will use the new version.
    overridePackages = f: applyGlobalOverrides f;
  
    # Override system. This is useful to build i686 packages on x86_64-linux.
    forceSystem = system: kernel: (import ./../..) {
  
negative.code:   # Return the complete set of packages, after applying the overrides
    # returned by the `overrider' function (see above).  Warning: this
    # function is very expensive!
    pkgsWithOverrides = overrider:
      let
        overrides = super: overrider pkgs super // stdenvOverrides super;
  
  