Comment 7 for bug 1698181

apt-get upgraded lxc container just now, shows:

root@a2:~# apt-get remove ifupdown
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
  ifenslave ifupdown resolvconf ubuntu-minimal
0 upgraded, 0 newly installed, 4 to remove and 0 not upgraded.
After this operation, 543 kB disk space will be freed.
Do you want to continue? [Y/n] n
Abort.
root@a2:~# cat /etc/cloud/build.info
build_name: server
serial: 20170725

Also note
# apt-cache rdepends ifenslave
ifenslave
Reverse Depends:
  ifenslave-2.6
  ubuntu-server

So thats another change we probably need for ubuntu-meta/seeds.