anchor.diff:    zsnes = { type = "job"; systems = ["x86_64-linux"]; schedulingPriority = 4; };
     zynaddsubfx = { type = "job"; systems = ["x86_64-linux"]; schedulingPriority = 4; };
     zziplib = { type = "job"; systems = ["x86_64-linux"]; schedulingPriority = 4; };
  -})
  +});
  +
  +in jobs
  
positive.code:           (n: v: (v.type or null) == "derivation")
            attrset)));
  
  in
  {
  
    tarball = import ./make-tarball.nix;
  
  } // (mapTestOn rec {
  
    a2jmidid = { type = "job"; systems = ["x86_64-linux"]; schedulingPriority = 4; };
    aacskeys = { type = "job"; systems = ["x86_64-linux"]; schedulingPriority = 4; };
  
negative.code: /*
     test for example like this
     $ nix-build pkgs/top-level/release-python.nix
  */
  
  { 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" "x86_64-freebsd" "i686-freebsd" ]
  }:
  
  with import ./release-lib.nix {inherit supportedSystems; };
  
  let
    jobsForDerivations = attrset: pkgs.lib.attrsets.listToAttrs
  