yosys: 0.9+4052 -> 0.9+4221

stdenv.mkDerivation rec {

  pname   = "yosys";

  version = "0.9+4052";

  version = "0.9+4221";

  src = fetchFromGitHub {

    owner  = "YosysHQ";

    repo   = "yosys";

    rev    = "687f381b6985d9dda7e11535628e2fafff267af5";

    sha256 = "15lcj798ckh9zwvdqb5gnvicilsxjyxv01gcviijg310hq62n7vf";

    rev    = "9600f20be887b707f6d5d3f74dec58b336e2464e";

    sha256 = "0xbvbnhc6qvcq1c8zxfyf4ws959c824z660nrghfxyzkrjl8wi1h";

  };

  enableParallelBuilding = true;