anchor.diff:      "mirror://gnu/gzip/gzip-${version}.tar.xz"
     ];
   
  -  version = "1.8";
  +  version = "1.9";
   in
   stdenv.mkDerivation rec {
     name = "gzip-${version}";
  
positive.code:   passthru = {
      srcVerification = fetchurl rec {
        failEarly = true;
        urls = tarballUrls "1.8";
        pgpsigUrls = map (n: "${n}.sig") urls;
        pgpKeyFingerprint = "155D 3FC5 00C8 3448 6D1E  EA67 7FD9 FCCB 000B EEEE";
        outputHash = "ff1767ec444f71e5daf8972f6f8bf68cfcca1d2f76c248eb18e8741fc91dbbd3";
        inherit (src) outputHashAlgo;
      };
    };
  
negative.code:   src = fetchurl {
      urls = tarballUrls version;
      hashOutput = false;
      sha256 = "ae506144fc198bd8f81f1f4ad19ce63d5a2d65e42333255977cf1dcf1479089a";
    };
  
    # In stdenv-linux, prevent a dependency on bootstrap-tools.
  