anchor.diff:  
     canEfi = any (system: stdenv.system == system) (mapAttrsToList (name: _: name) efiSystems);
   
  -  prefix = "grub${if efiSupport then "-efi" else ""}";
  +  prefix = "grub${if efiSupport then "-efi" else ""}${optionalString zfsSupport "-zfs"}";
   
  -  version = "2.02-beta2";
  +  version = "2.02-git-1de3a4";
   
     unifont_bdf = fetchurl {
       url = "http://unifoundry.com/unifont-5.1.20080820.bdf.gz";
  
positive.code: stdenv.mkDerivation rec {
    name = "${prefix}-${version}";
  
    src = fetchurl {
      name = "grub-2.02-beta2.tar.xz";
      url = "http://alpha.gnu.org/gnu/grub/grub-2.02~beta2.tar.xz";
      sha256 = "13a13fhc0wf473dn73zhga15mjvkg6vqp4h25dxg4n7am2r05izn";
    };
  
    nativeBuildInputs = [ autogen flex bison python autoconf automake ];
  
negative.code: { stdenv, fetchurl, fetchgit, autogen, flex, bison, python, autoconf, automake
  , gettext, ncurses, libusb, freetype, qemu, devicemapper
  , linuxPackages ? null
  , efiSupport ? false
  