grub: Doesn't support building bios and efi simultaneously

pkgs/tools/misc/grub/2.0x.nix

@@ -1,7 +1,7 @@
 { stdenv, fetchurl, fetchgit, autogen, flex, bison, python, autoconf, automake
 , gettext, ncurses, libusb, freetype, qemu, devicemapper
 , zfs ? null
-, efiSupport ? true
+, efiSupport ? false
 , zfsSupport ? true
 }:
 

pkgs/top-level/all-packages.nix

@@ -1456,8 +1456,11 @@ let
 
   grub2_full = callPackage ../tools/misc/grub/2.0x.nix { };
 
+  grub2_efi = grub2_full.override {
+    efiSupport = true;
+  };
+
   grub2_light = grub2_full.override {
-    efiSupport = false;
     zfsSupport = false;
   };