anchor.diff:  
   
     versionModule =
  -    { system.nixosVersionSuffix = pkgs.lib.optionalString (!officialRelease) versionSuffix;  };
  +    { system.nixosVersionSuffix = versionSuffix;  };
   
   
     makeIso =
  
positive.code: { nixpkgs ? { outPath = ./..; revCount = 5678; shortRev = "gfedcba"; }
  , officialRelease ? false
  }:
  
  let
  
    version = builtins.readFile ../.version;
    versionSuffix = "pre${toString nixpkgs.revCount}_${nixpkgs.shortRev}";
  
    systems = [ "x86_64-linux" "i686-linux" ];
  
  
negative.code: 
        src = nixpkgs;
  
        officialRelease = false; # FIXME: fix this in makeSourceTarball
        inherit version versionSuffix;
  
        buildInputs = [ pkgs.nixUnstable ];
  
  