anchor.diff:    passthru = {
       srcVerification = fetchurl rec {
         failEarly = true;
  -      urls = tarballUrls "1.25";
  +      urls = tarballUrls "1.26";
         pgpsigUrls = map (n: "${n}.sig") urls;
         inherit (gnupg.srcVerification) pgpKeyFingerprints;
  -      outputHash = "f628f75843433b38b05af248121beb7db5bd54bb2106f384edac39934261320c";
  +      outputHash = "4c4bcbc90116932e3acd37b37812d8653b1b189c1904985898e860af818aee69";
         inherit (src) outputHashAlgo;
       };
     };
  
positive.code:     "mirror://gnupg/libgpg-error/libgpg-error-${version}.tar.bz2"
    ];
  
    version = "1.25";
  in
  stdenv.mkDerivation rec {
    name = "libgpg-error-${version}";
  
negative.code:   src = fetchurl {
      urls = tarballUrls version;
      hashOutput = false;
      sha256 = "4c4bcbc90116932e3acd37b37812d8653b1b189c1904985898e860af818aee69";
    };
  
    postPatch = ''
  