anchor.diff:  rec {
   
     
  -  nixpkgsRel = "nixpkgs-0.12pre10553";
  +  nixpkgsRel = "nixpkgs-0.12pre11712-4lrp7j8x";
   
   
     configuration = {
  
positive.code:     };
      
      installer = {
        nixpkgsURL = http://nix.cs.uu.nl/dist/nix/ + nixpkgsRel;
      };
  
      security = {
  
negative.code: 
    # Get a recent copy of Nixpkgs.
    nixpkgsTarball = pkgs.fetchurl {
      url = configuration.installer.nixpkgsURL + "/nixexprs.tar.bz2";
      sha256 = "af5983ce0ac4bb5ad7786905d20fe4ae6bd4c43f6c831baa42bf15f09535dba4";
    };
  
  
  