divert /usr/bin/systemd-detect-virt as part of the grub diversions, so

that the grub kernel postinst hook is operational when we're building
in a container.  LP: #1729034.

debian/changelog

@@ -3,6 +3,9 @@ livecd-rootfs (2.479) UNRELEASED; urgency=medium
   * Purge initramfs-tools from minimized images.
   * Make sure to remove any initramfs that was generated in a minimized
     image.
+  * divert /usr/bin/systemd-detect-virt as part of the grub diversions, so
+    that the grub kernel postinst hook is operational when we're building
+    in a container.  LP: #1729034.
 
  -- Steve Langasek <steve.langasek@ubuntu.com>  Fri, 13 Oct 2017 17:14:58 -0400
 

live-build/functions

@@ -300,6 +300,15 @@ divert_grub() {
 	chroot "$CHROOT_ROOT" dpkg-divert --local \
 		--divert /etc/grub.d/30_os-prober.dpkg-divert \
 		--rename /etc/grub.d/30_os-prober
+
+	# Divert systemd-detect-virt; /etc/kernel/postinst.d/zz-update-grub
+	# no-ops if we are in a container, and the launchpad farm runs builds
+	# in lxd.  We therefore pretend that we're never in a container (by
+	# exiting 1).
+	chroot "$CHROOT_ROOT" dpkg-divert --local \
+		--rename /usr/bin/systemd-detect-virt
+	echo "exit 1" > "$CHROOT_ROOT"/usr/bin/systemd-detect-virt
+	chmod +x "$CHROOT_ROOT"/usr/bin/systemd-detect-virt
 }
 
 undivert_grub() {
@@ -312,4 +321,8 @@ undivert_grub() {
 	chroot "$CHROOT_ROOT" dpkg-divert --remove --local \
 		--divert /etc/grub.d/30_os-prober.dpkg-divert \
 		--rename /etc/grub.d/30_os-prober
+
+	rm "$CHROOT_ROOT"/usr/bin/systemd-detect-virt
+	chroot "$CHROOT_ROOT" dpkg-divert --remove --local \
+		--rename /usr/bin/systemd-detect-virt
 }