anchor.diff:    passthru = {
       srcVerification = fetchurl rec {
         failEarly = true;
  -      urls = tarballUrls "1.28";
  +      urls = tarballUrls "1.29";
         pgpsigUrls = map (n: "${n}.sig") urls;
         inherit (gnupg.srcVerification) pgpKeyFingerprints;
  -      outputHash = "3edb957744905412f30de3e25da18682cbe509541e18cd3b8f9df695a075da49";
  +      outputHash = "ece926fa5719d17a7ad8da618712cfa2f8a796ab2f2af9d544c5bb093383b1ea";
         inherit (src) outputHashAlgo;
       };
     };
  
positive.code:     "mirror://gnupg/libgpg-error/libgpg-error-${version}.tar.bz2"
    ];
  
    version = "1.28";
  in
  stdenv.mkDerivation rec {
    name = "libgpg-error-${version}";
  
negative.code:   src = fetchurl {
      urls = tarballUrls version;
      hashOutput = false;
      sha256 = "ece926fa5719d17a7ad8da618712cfa2f8a796ab2f2af9d544c5bb093383b1ea";
    };
  
    postPatch = ''
  