Comment 6 for bug 1845337

The 'good' tests have a dir being mounted '/dev/.lxd-mounts' while the 'bad' tests have a dir being mounted '/dev/.lxc' as well as '/dev/.lxc/proc'. In the 'bad' case, the test is making sure there are no unexpected writable directories other than the single one it's expecting (and other expected ones which are ignored, e.g. /tmp, /var/tmp, ...), and it's finding a writable dir under /dev/.lxc/ that it of course wasn't expecting:
+ test /dev/.lxc/proc/1079/fd/dev/.lxc/proc/1079/map_files/dev/.lxc/proc/1079/task/1079/fd/var/lib/private/quux/pief/var/lib/private/waldo = /var/lib/private/quux/pief/var/lib/private/waldo

something (maybe lxc itself?) seems to be mounting /proc under the /dev/.lxc dir, or something like that...when using lxd, that problem doesn't seem to happen. I'd be inclined to blame lxc for this, not the test itself.

Did the armhf testbeds get changed from lxd to lxc recently?