anchor.diff: -{ stdenv, fetchurl, fetchgit, pkgconfig
  +{ stdenv, fetchurl, fetchgit, fetchpatch, pkgconfig
   , qt4, qmake4Hook, qt5, avahi, boost, libopus, libsndfile, protobuf, speex, libcap
   , alsaLib, python
   , jackSupport ? false, libjack2 ? null
  
positive.code:   generic = overrides: source: stdenv.mkDerivation (source // overrides // {
      name = "${overrides.type}-${source.version}";
  
      patches = optional jackSupport ./mumble-jack-support.patch;
  
      nativeBuildInputs = [ pkgconfig python ]
        ++ { qt4 = [ qmake4Hook ]; qt5 = [ qt5.qmake ]; }."qt${toString source.qtVersion}"
  
negative.code:       url = "https://github.com/mumble-voip/mumble/releases/download/${version}/mumble-${version}.tar.gz";
        sha256 = "1s60vaici3v034jzzi20x23hsj6mkjlc0glipjq4hffrg9qgnizh";
      };
  
      # Fix compile error against boost 1.66 (#33655):
      patches = singleton (fetchpatch {
        url = "https://github.com/mumble-voip/mumble/commit/"
            + "ea861fe86743c8402bbad77d8d1dd9de8dce447e.patch";
        sha256 = "1r50dc8dcl6jmbj4abhnay9div7y56kpmajzqd7ql0pm853agwbh";
      });
    };
  
    gitSource = rec {
  