Comment 7 for bug 1993836

Okay the following command works as a hack to test an older squashfs.

$ sudo wget -O /var/lib/maas/boot-resources/current/ubuntu/amd64/generic/focal/stable/squashfs \
    https://images.maas.io/ephemeral-v3/stable/focal/amd64/20221010/squashfs

and grown-swift.maas (system_id: aa3ktf) has succeeded with squashfs 20221010 with focal.