Comment 8 for bug 1824407

BTW, I can generate the mount move failure with the cut down script as follows (which follows the same mount patterns as the casper script)

#!/bin/bash -x
mkdir -p /cdrom
mount -t iso9660 -o ro,noatime /dev/sr0 /cdrom
sleep 1
mkdir -p /cow
mount -t tmpfs -o 'rw,noatime,mode=755' tmpfs /cow
sleep 1
mkdir -p /cow/upper
mkdir -p /cow/work
modprobe -q -b overlay
sleep 1
modprobe -q -b loop
sleep 1
dev=$(losetup -f)
mkdir -p /filesystem.squashfs
losetup $dev /cdrom/casper/filesystem.squashfs
mount -t squashfs -o ro,noatime $dev /filesystem.squashfs
sleep 1

dev=$(losetup -f)
mkdir -p /installer.squashfs
losetup $dev /cdrom/casper/installer.squashfs
mount -t squashfs -o ro,noatime $dev /installer.squashfs
sleep 1

mount -t overlay -o 'upperdir=/cow/upper,lowerdir=/installer.squashfs:/filesystem.squashfs,workdir=/cow/work' /cow /root

mkdir -p /root/rofs
mount -o move /filesystem.squashfs /root/rofs