anchor.diff:    passthru = {
       srcVerification = fetchurl rec {
         failEarly = true;
  -      urls = tarballUrls "2.4.4";
  +      urls = tarballUrls "2.5.1";
         pgpsigUrls = map (n: "${n}.sig") urls;
         inherit (gnupg.srcVerification) pgpKeyFingerprints;
  -      outputHash = "9e69a102272324de0bb56025779f84fd44901afcc6eac51505f6a63ea5737ca1";
  +      outputHash = "47f96c37b4f2aac289f0bc1bacfa8bd8b4b209a488d3d15e2229cb6cc9b26449";
         inherit (src) outputHashAlgo;
       };
     };
  
positive.code:   src = fetchurl {
      urls = tarballUrls version;
      hashOutput = false;
      sha256 = "9e69a102272324de0bb56025779f84fd44901afcc6eac51505f6a63ea5737ca1";
    };
  
    buildInputs = [
  
negative.code:     "mirror://gnupg/libassuan/libassuan-${version}.tar.bz2"
    ];
  
    version = "2.5.1";
  in
  stdenv.mkDerivation rec {
    name = "libassuan-${version}";
  