From a75544e0c3eb41dd218d77054095b8c67b9d6e3a Mon Sep 17 00:00:00 2001
From: Mathieu Trudel-Lapierre <mathieu.trudel-lapierre@canonical.com>
Date: Wed, 23 Aug 2017 19:20:35 -0400
Subject: [PATCH] Only set a default GRUB_PRELOAD_MODULES if not already
 defined; otherwise used the existing values.

---
 live-build/ubuntu-cpc/hooks/033-disk-image-uefi.binary | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/live-build/ubuntu-cpc/hooks/033-disk-image-uefi.binary b/live-build/ubuntu-cpc/hooks/033-disk-image-uefi.binary
index 9594c0d3..600213eb 100755
--- a/live-build/ubuntu-cpc/hooks/033-disk-image-uefi.binary
+++ b/live-build/ubuntu-cpc/hooks/033-disk-image-uefi.binary
@@ -82,8 +82,9 @@ install_grub() {
     cat << EOF >> mountpoint/etc/default/grub.d/50-cloudimg-settings.cfg
 ${CLOUD_IMG_STR}
 # For Cloud Image compatability
-GRUB_PRELOAD_MODULES="${grub_modules}"
+GRUB_PRELOAD_MODULES="${GRUB_PRELOAD_MODULES:-$grub_modules}"
 EOF
+
     chroot mountpoint grub-install "${loop_device}" \
         --boot-directory=/boot \
         --efi-directory=/boot/efi \