anchor.diff:  
     enableParallelBuilding = true;
   
  +  configureFlags = [ "--with-spdylay=no" "--disable-examples" "--disable-python-bindings" ]
  +    ++ optional enableAsioLib "--enable-asio-lib --with-boost-libdir=${boost}/lib";
  +
  +  #doCheck = true;  # requires CUnit ; currently failing at test_util_localtime_date in util_test.cc
  +
  +
     meta = with stdenv.lib; {
  -    homepage = http://nghttp2.org/;
  +    homepage = https://nghttp2.org/;
       description = "A C implementation of HTTP/2";
       license = licenses.mit;
       platforms = platforms.all;
  
positive.code: 
  stdenv.mkDerivation rec {
    name = "nghttp2-${version}";
    version = "1.19.0";
  
    # Don't use fetchFromGitHub since this needs a bootstrap curl
    src = fetchurl {
      url = "https://github.com/nghttp2/nghttp2/releases/download/v${version}/nghttp2-${version}.tar.bz2";
      sha256 = "477466eee27158d37b4478d9335dd091497cae4d7f2375fc6657beab67db9e7a";
    };
  
    outputs = [ "out" "dev" "lib" ];
  
    nativeBuildInputs = [ pkgconfig ];
    buildInputs = [ openssl libev zlib libcares ]
      ++ optional enableHpack jansson
      ++ optional enableAsioLib boost
      ++ optional enableGetAssets libxml2
  
negative.code: { stdenv, fetchurl, pkgconfig
  
  # Optional Dependencies
  , openssl ? null, libev ? null, zlib ? null, c-ares ? null
  , enableHpack ? false, jansson ? null
  , enableAsioLib ? false, boost ? null
  , enableGetAssets ? false, libxml2 ? null
  