anchor.diff: -{ stdenv, fetchurl, pkgconfig, libsepol, pcre }:
  +{ stdenv, fetchurl, pkgconfig, libsepol, pcre
  +, enablePython ? false, swig ? null, python ? null
  +}:
  +
  +assert enablePython -> swig != null && python != null;
  +
  +with stdenv.lib;
   
   stdenv.mkDerivation rec {
     name = "libselinux-${version}";
  
positive.code:     done
    '';
  
    preInstall = '' makeFlags="$makeFlags PREFIX=$out DESTDIR=$out" '';
  
    meta = {
      inherit (libsepol.meta) homepage platforms maintainers;
  
negative.code: 
    patches = [ ./fPIC.patch ]; # libsemanage seems to need -fPIC everywhere
  
    buildInputs = [ pkgconfig libsepol pcre ]
               ++ optionals enablePython [ swig python ];
  
    prePatch = ''
      tar xvf ${patch_src}
  