Mount using --make-rslave to ensure safe unmounts for rbind mounts

debian/changelog

@@ -13,6 +13,9 @@ livecd-rootfs (2.408.19) UNRELEASED; urgency=medium
   * Also nuke the sleep / udevadm settle calls in the process, which should
     never be required and slow down the builds.
 
+  [ Balint Reczey ]
+  * Mount using --make-rslave to ensure safe unmounts for rbind mounts
+
  -- Victor Tapia <victor.tapia@canonical.com>  Tue, 19 Sep 2017 10:55:11 +0200
 
 livecd-rootfs (2.408.18) xenial; urgency=medium

live-build/ubuntu-cpc/functions

@@ -82,7 +82,7 @@ mount_image() {
 setup_mountpoint() {
     local mountpoint="$1"
 
-    mount --rbind /dev "$mountpoint/dev"
+    mount --rbind --make-rslave /dev "$mountpoint/dev"
     mount proc-live -t proc "$mountpoint/proc"
     mount sysfs-live -t sysfs "$mountpoint/sys"
     mount -t tmpfs none "$mountpoint/tmp"