Comment 2 for bug 2049271

Here I tried to completely cover it:

- create two virtual disks
- on each disk
  - create a single MBR partition over the whole disk
  - format the partition as ext4

- create a virtual machine with the disks attached
- install jammy server minimal onto sda1
- boot the vm

- just in case, disable swap
  - run "sudo swapoff -a"
  - drop the swap line in /etc/fstab
  - delete /swapfile

- run "sudo mkdir /disk1"
- in /etc/fstab mount sdb1 as /disk1 with such options:

    /dev/sdb1 /disk1 ext4 nofail,x-systemd.device-timeout=10 0 2

- run "sudo mount -a"
- checkpoint:

    > mount | grep /dev/sd
    /dev/sda1 on / type ext4 (rw,relatime)
    /dev/sdb1 on /disk1 type ext4 (rw,relatime)

- run "sudo apt install overlayroot -y"

[1] - reboot and keep Shift pressed to stop at grub menu
[2] - in grub, press "e" to edit the boot entry
[3] - in the "linux ..." line append "overlayroot=tmpfs"
[4] - press Ctrl+X to boot

- checkpoint:

    > mount | grep overlay
    overlayroot on / type overlay ..
    /media/root-ro/disk1 on /disk1 type overlay ..

- shutdown the machine
- detach the second disk
- repeat [1]..[4]

- notice there is a 10s countdown waiting for the second disk
- checkpoint:

    You are in emergency mode. After logging in, type "journalctl -xb" to view system logs,
    "systemctl reboot" to reboot, "systemctl default" or "exit" to boot into default mode.
    Press Enter for maintenance
    (or press Control-D to ocntinue):

- press Enter
- run "journalctl -b -o cat | grep local-fs"
- checkpoint:

    local-fs.target: Job local-fs.target/start failed with result 'dependency'.
    local-fs.target: Triggering OnFailure= dependencies.

Full output of "journalctl -xb" from a failed boot attempt attached