anchor.diff:  }:
   
   stdenv.mkDerivation rec {
  -  name = "libxcb-1.13";
  +  name = "libxcb-1.13.1";
   
     src = fetchurl {
       url = "mirror://xorg/individual/xcb/${name}.tar.bz2";
       hashOutput = false;
  -    sha256 = "188c8752193c50ff2dbe89db4554c63df2e26a2e47b0fa415a70918b5b851daa";
  +    sha256 = "a89fb7af7a11f43d2ce84a844a4b38df688c092bf4b67683aef179cdf2a647c4";
     };
   
     nativeBuildInputs = [
  
positive.code:         outputHash
          outputHashAlgo
          urls;
        pgpsigUrls = map (n: "${n}.sig") src.urls;
        pgpKeyFingerprints = [
          # Daniel Stone
          "A66D 805F 7C93 29B4 C5D8  2767 CCC4 F07F AC64 1EFF"
        ];
        failEarly = true;
      };
    };
  
negative.code:     "--enable-selective-werror"
      "--disable-strict-compilation"
      "--disable-devel-docs"
      "--enable-dri3"
      "--enable-xevie"
      "--enable-xprint"
      "--enable-selinux"
      "--without-doxygen"
      "--without-launchd"
    ];
  
    passthru = {
  