Comment 1 for bug 1815231

I'm working on reproducing this, I was able to reproduce a similar condition in a charm-upgrade:

2019-02-08 20:39:12 DEBUG upgrade-charm Unpacking python-markupsafe (1.0-1build1) ...
2019-02-08 20:39:12 DEBUG upgrade-charm Selecting previously unselected package python-jinja2.
2019-02-08 20:39:12 DEBUG upgrade-charm Preparing to unpack .../python-jinja2_2.10-1_all.deb ...
2019-02-08 20:39:12 DEBUG upgrade-charm Unpacking python-jinja2 (2.10-1) ...
2019-02-08 20:39:12 DEBUG upgrade-charm Setting up python-markupsafe (1.0-1build1) ...
2019-02-08 20:39:12 DEBUG upgrade-charm Setting up python-jinja2 (2.10-1) ...
2019-02-08 20:39:14 DEBUG upgrade-charm Traceback (most recent call last):
2019-02-08 20:39:14 DEBUG upgrade-charm File "/var/lib/juju/agents/unit-ceph-radosgw-0/charm/hooks/upgrade-charm", line 90, in <module>
2019-02-08 20:39:14 DEBUG upgrade-charm from charmhelpers.contrib.hardening.harden import harden
2019-02-08 20:39:14 DEBUG upgrade-charm File "/var/lib/juju/agents/unit-ceph-radosgw-0/charm/hooks/charmhelpers/contrib/hardening/harden.py", line 25, in <module>
2019-02-08 20:39:14 DEBUG upgrade-charm from charmhelpers.contrib.hardening.host.checks import run_os_checks
2019-02-08 20:39:14 DEBUG upgrade-charm File "/var/lib/juju/agents/unit-ceph-radosgw-0/charm/hooks/charmhelpers/contrib/hardening/host/checks/__init__.py", line 19, in <module>
2019-02-08 20:39:14 DEBUG upgrade-charm from charmhelpers.contrib.hardening.host.checks import (
2019-02-08 20:39:14 DEBUG upgrade-charm File "/var/lib/juju/agents/unit-ceph-radosgw-0/charm/hooks/charmhelpers/contrib/hardening/host/checks/apt.py", line 16, in <module>
2019-02-08 20:39:14 DEBUG upgrade-charm from charmhelpers.contrib.hardening.audits.apt import (
2019-02-08 20:39:14 DEBUG upgrade-charm File "/var/lib/juju/agents/unit-ceph-radosgw-0/charm/hooks/charmhelpers/contrib/hardening/audits/apt.py", line 16, in <module>
2019-02-08 20:39:14 DEBUG upgrade-charm from apt import apt_pkg
2019-02-08 20:39:14 DEBUG upgrade-charm ImportError: No module named apt
2019-02-08 20:39:14 ERROR juju.worker.uniter.operation runhook.go:132 hook "upgrade-charm" failed: exit status 1