anchor.diff:  { nixpkgs ? { outPath = (import ./all-packages.nix {}).lib.cleanSource ../..; revCount = 1234; shortRev = "abcdef"; }
   , officialRelease ? false
   , # The platforms for which we build Nixpkgs.
  -  supportedSystems ? [ "x86_64-linux" "i686-linux" "x86_64-darwin" ]
  +  supportedSystems ? [ "x86_64-linux" "i686-linux" ]
   , scrubJobs ? true
   }:
   
  
positive.code:               jobs.lib-tests
                jobs.stdenv.x86_64-linux
                jobs.stdenv.i686-linux
                jobs.stdenv.x86_64-darwin
                jobs.linux.x86_64-linux
                jobs.linux.i686-linux
                jobs.python.x86_64-linux
                jobs.python.i686-linux
                jobs.python.x86_64-darwin
                jobs.python3.x86_64-linux
                jobs.python3.i686-linux
                jobs.python3.x86_64-darwin
                # Ensure that X11/GTK+ are in order.
                jobs.thunderbird.x86_64-linux
                jobs.thunderbird.i686-linux
                # Ensure that basic stuff works on darwin
                jobs.git.x86_64-darwin
                jobs.mysql.x86_64-darwin
                jobs.vim.x86_64-darwin
              ] ++ lib.collect lib.isDerivation jobs.stdenvBootstrapTools;
          };
  
  
negative.code:       abcde = linux;
        aspell = all;
        atlas = linux;
        bazaar = linux;
        binutils = linux;
        bind = linux;
        bvi = all;
  