anchor.diff:                                    install -D ${fetchurl { inherit url sha1; }} $out/${name}
                                     echo -n ${sha1} > $out/${name}.sha1
                                   '') list}
  +        find $out -exec touch -c -m -r '{}' --date="1980-01-01" '{}' \;
         '';
       };
   
  
positive.code: 
    # copy of pkgs.oraclejvm8 with JVMCI interface (TODO: it should work with pkgs.openjdk8 too)
    jvmci8 = stdenv.mkDerivation rec {
      version = "0.45";
      name = let
               n = "jvmci8u171-${version}";
             in if (lib.stringLength n) == (lib.stringLength oraclejdk8.name) then
                  n
                else
  
negative.code:       owner  = "graalvm";
        repo   = "graal-jvmci-8";
        rev    = "jvmci-${version}";
        sha256 = "1zgin0w1qa7wmfhcisx470fhnmddfxxp5nyyix31yaa7dznql82k";
      };
      buildInputs = [ mx mercurial ];
      postUnpack = ''
  