prepare final 2.06 release

grub.install

@@ -8,7 +8,8 @@ post_upgrade() {
   fi
 
   # https://md.archlinux.org/F1JuYj5xQtWyhvH8_ilErg#
-  cat <<EOM
+  if [[ -e /sys/firmware/efi/efivars ]]; then
+    cat <<EOM
 :: Recent versions of grub may fail to boot with secure boot enabled. The
    message will look like this:
     > error: verification requested but nobody cares:
@@ -17,6 +18,7 @@ post_upgrade() {
    Handle installation to UEFI with care and be prepared!
    For details see: https://md.archlinux.org/F1JuYj5xQtWyhvH8_ilErg#
 EOM
+  fi
 }
 
 post_install() {