Comment 5 for bug 1699065

# trusty container - systemd and ssd not installed
# install works
$ apt install sssd
# Fake "upgrade" works as well
$ apt install sssd --reinstall

# clean again
$ apt remove --purge sssd && apt-get autoremove

# no pulling in snap + deps
# ubuntu-core-launcher -> snap-confine -> snapd (former transitionals)
$apt install snapd
[...]
The following NEW packages will be installed:
  crda grub-common grub-gfxpayload-lists grub-pc grub-pc-bin grub2-common iw
  libfreetype6 liblzo2-2 libnl-genl-3-200 libsystemd-journal0 linux-firmware
  linux-generic-lts-xenial linux-headers-4.4.0-81
  linux-headers-4.4.0-81-generic linux-headers-generic-lts-xenial
  linux-image-4.4.0-81-generic linux-image-extra-4.4.0-81-generic
  linux-image-generic-lts-xenial os-prober snapd squashfs-tools systemd
  thermald wireless-regdb

Hrm, checking deeper where your issue might come from ...