anchor.diff:  in
     assert oldVer -> stdenv.isDarwin; # reduce likelihood of using old libxml2 unintentionally
   
  -stdenv.mkDerivation rec {
  +let
  +libxml = stdenv.mkDerivation rec {
     pname = "libxml2";
  -  version = if oldVer then "2.10.1" else
  -    "2.10.2";
  +  version = "2.10.2";
   
     outputs = [ "bin" "dev" "out" "doc" ]
       ++ lib.optional pythonSupport "py"
  
positive.code:     platforms = platforms.all;
      maintainers = with maintainers; [ eelco jtojnar ];
    };
  }
  
negative.code:   outputMan = "bin";
  
    src = fetchurl {
      url = "mirror://gnome/sources/libxml2/${lib.versions.majorMinor version}/libxml2-${version}.tar.xz";
      sha256 = "0kCr5tqcZcsZAN2b86NQHM+Is8Khy5gxfQPyct2lsmU=";
    };
  
    patches = [
  