juju 2.9.0 client doesn't recognize lxd machines during series-upgrade

[Drew Freiberger]

While using the 2.9.0 juju client snap, running 'series-upgrade prepare' against an lxd target on a 2.8.10 model results in:

$ juju upgrade-series 19/lxd/13 prepare bionic -y
ERROR machine "19/lxd/13" not found

Downgrading to 2.8/latest snap resolves the issue.

$ juju version
2.8.10-xenial-amd64
$ juju upgrade-series 19/lxd/13 prepare bionic -y
machine-19-lxd-13 started upgrade series from "xenial" to "bionic"
hacluster-mysql/291 pre-series-upgrade hook running
hacluster-mysql/291 pre-series-upgrade completed
mysql/6 pre-series-upgrade hook running
mysql/6 pre-series-upgrade completed
nrpe-container/497 pre-series-upgrade hook running
nrpe-container/497 pre-series-upgrade hook not found, skipping
landscape-client/865 pre-series-upgrade hook running
landscape-client/865 pre-series-upgrade hook not found, skipping
filebeat/855 pre-series-upgrade hook running
filebeat/855 pre-series-upgrade completed
telegraf/861 pre-series-upgrade hook running
telegraf/861 pre-series-upgrade completed
machine-19-lxd-13 binaries and service files written

Juju is now ready for the series to be updated.
Perform any manual steps required along with "do-release-upgrade".
When ready, run the following to complete the upgrade series process:

juju upgrade-series 19/lxd/13 complete

[Simon Richardson (simonrichardson)]

Juju PR: https://github.com/juju/juju/pull/12994