Add replace_grub_root_with_label function thereby consolidating multiple

uses of the same calls to sed. Thanks to Dan Watkins.

debian/changelog

@@ -17,6 +17,8 @@ livecd-rootfs (2.440) UNRELEASED; urgency=medium
   * Fix the OVF's metadata to include Ubuntu specific identifiers and
     descriptions instead of the generic Linux ones. Thanks to Chris Glass.
     (LP: #1656293)
+  * Add replace_grub_root_with_label function thereby consolidating multiple
+    uses of the same calls to sed. Thanks to Dan Watkins.
 
   [ Adam Conrad ]
   * Set device_tree_address for the new kernel in the RPi bootloader config.txt

live-build/ubuntu-cpc/functions

@@ -249,4 +249,11 @@ convert_to_qcow2() {
     qemu-img info "$destination"
 }
 
+replace_grub_root_with_label() {
+    # When update-grub is run, it will detect the disks in the build system.
+    # Instead, we want grub to use the cloudimg-rootfs labelled disk
+    CHROOT_ROOT="$1"
 
+    sed -i -e "s,root=[^ ]\+,root=LABEL=cloudimg-rootfs," \
+        "$CHROOT_ROOT/boot/grub/grub.cfg"
+}

live-build/ubuntu-cpc/hooks/033-disk-image-uefi.binary

@@ -105,7 +105,7 @@ EOF
 
     chroot mountpoint dpkg-divert --local --rename /etc/grub.d/30_os-prober
     chroot mountpoint update-grub
-    sed -i "s,root=.* ,root=LABEL=cloudimg-rootfs ,g" mountpoint/boot/grub/grub.cfg
+    replace_grub_root_with_label mountpoint
     chroot mountpoint dpkg-divert --remove --local --rename /etc/grub.d/30_os-prober
 
     chroot mountpoint apt-get -y clean

live-build/ubuntu-cpc/hooks/034-disk-image-ppc64el.binary

@@ -52,7 +52,7 @@ EOF
 
     chroot mountpoint dpkg-divert --local --rename /etc/grub.d/30_os-prober
     chroot mountpoint update-grub
-    sed -i "s,root=.* ,root=LABEL=cloudimg-rootfs ,g" mountpoint/boot/grub/grub.cfg
+    replace_grub_root_with_label mountpoint
     chroot mountpoint dpkg-divert --remove --local --rename /etc/grub.d/30_os-prober
 
     umount_partition mountpoint