Comment 2 for bug 1592505

This was recreatable in xenial lxc (no yakkety lxc images yet) with:

$ lxc launch xenial x1
$ sleep 10
$ lxc exec x1 -- sh -c 'add-apt-repository -y ppa:cloud-init-dev/daily && apt-get update && apt-get install cloud-init'
$ lxc exec x1 -- sh -c '( cd /var/lib/cloud/ && for d in *; do [ "$d" = "seed" ] || rm -Rf $d; done ); rm -Rf /var/log/cloud*'
$ lxc exec x1 reboot

the above basically cleans the image making it think its first boot.
Then, one more time:

$ lxc exec x1 reboot

$ lxc exec x1 grep WARN /var/log/cloud-init.log