anchor.diff:  
   , boost
   , openssl
  -, pythonPackages
  +, python3Packages
   , zlib
   
   , channel
  
positive.code:     (libtorrentOlder "1.1" "--disable-geoip")
      "--disable-examples"
      "--disable-tests"
      "--${boolEn (pythonPackages.python != null)}-python-binding"
      "--with-boost=${boost.dev}"
      "--with-boost-libdir=${boost.lib}/lib"
      (libtorrentOlder "1.1" "--without-libgeoip")
  
negative.code:     };
      "1.1-head" = {
        fetchzipversion = 6;
        version = "2019-05-22";
        rev = "3eac1700a1b5a8403b9353477d47b1d1535440d8";
        sha256 = "65f9112f9b66d4ebb6ee66b39b1e15e2af383e9226c0bba5c34279a8dd899041";
      };
      "head" = {
        fetchzipversion = 2;
  