juju doesn't surface cloud-init failures

This bug is similar to bug 1644566, though the underlying reason doesn't seem to be the same. On a fresh artful (this seems to affect at least zesty also) instance, I am unable to bootstrap a new lxd container. I have tried purging config and reinstalling lxd and juju from deb and snaps to various degress with no luck. The end result is juju stuck waiting at Attempting to connect to 10.249.132.39:22. See attached log. This is with lxd 2.16 and juju 2.2.2 or 2.3-alpah1.

$ lxc list
+---------------+---------+----------------------+------+------------+-----------+
| NAME | STATE | IPV4 | IPV6 | TYPE | SNAPSHOTS |
+---------------+---------+----------------------+------+------------+-----------+
| juju-759e30-0 | RUNNING | 10.249.132.39 (eth0) | | PERSISTENT | 0 |
+---------------+---------+----------------------+------+------------+-----------+
$ lxc network list
+--------+----------+---------+-------------+---------+
| NAME | TYPE | MANAGED | DESCRIPTION | USED BY |
+--------+----------+---------+-------------+---------+
| eno1 | physical | NO | | 0 |
+--------+----------+---------+-------------+---------+
| lxdbr0 | bridge | YES | | 1 |
+--------+----------+---------+-------------+---------+
$ ssh ubuntu@10.249.132.39
Warning: Permanently added '10.249.132.39' (ECDSA) to the list of known hosts.
Welcome to Ubuntu 16.04.2 LTS (GNU/Linux 4.11.0-10-generic x86_64)

 * Documentation: https://help.ubuntu.com
 * Management: https://landscape.canonical.com
 * Support: https://ubuntu.com/advantage

  Get cloud support with Ubuntu Advantage Cloud Guest:
    http://www.ubuntu.com/business/services/cloud

0 packages can be updated.
0 updates are security updates.

ubuntu@juju-759e30-0:~$ exit
logout
Connection to 10.249.132.39 closed.
$ lxc file pull juju-759e30-0/var/lib/cloud/seed/nocloud-net/meta-data -
#cloud-config
instance-id: juju-759e30-0
local-hostname: juju-759e30-0