Comment 1 for bug 2011361

FWIW, the lp:juju-upgrader is calling `juju create-backup` as follows:

| juju create-backup -m prodstack-is-beta:admin/controller --filename juju-backup-20230313-012205-prodstack-is-beta-ccf3a6e2-8f8e-4c4b-8caa-e425a9657be1.tar.gz