Upgrade to 18.11 charm fails

[Liam Young]

Upgrade from 18.08 charm to 18.11 for a Queens deployment fails with:

2018-11-14 18:41:20 INFO juju-log Installing python3-psutil with options: ['--option=Dpkg::Options::=--force-confold']
2018-11-14 18:41:20 DEBUG upgrade-charm Reading package lists...
2018-11-14 18:41:20 DEBUG upgrade-charm Building dependency tree...
2018-11-14 18:41:20 DEBUG upgrade-charm Reading state information...
2018-11-14 18:41:20 DEBUG upgrade-charm The following package was automatically installed and is no longer required:
2018-11-14 18:41:20 DEBUG upgrade-charm grub-pc-bin
2018-11-14 18:41:20 DEBUG upgrade-charm Use 'apt autoremove' to remove it.
2018-11-14 18:41:20 DEBUG upgrade-charm Suggested packages:
2018-11-14 18:41:20 DEBUG upgrade-charm python-psutil-doc
2018-11-14 18:41:20 DEBUG upgrade-charm The following NEW packages will be installed:
2018-11-14 18:41:20 DEBUG upgrade-charm python3-psutil
2018-11-14 18:41:20 DEBUG upgrade-charm 0 upgraded, 1 newly installed, 0 to remove and 5 not upgraded.
2018-11-14 18:41:20 DEBUG upgrade-charm Need to get 136 kB of archives.
2018-11-14 18:41:20 DEBUG upgrade-charm After this operation, 857 kB of additional disk space will be used.
2018-11-14 18:41:20 DEBUG upgrade-charm Get:1 http://nova.clouds.archive.ubuntu.com/ubuntu bionic/main amd64 python3-psutil amd64 5.4.2-1 [136 kB]
2018-11-14 18:41:21 DEBUG upgrade-charm Fetched 136 kB in 0s (417 kB/s)
2018-11-14 18:41:21 DEBUG upgrade-charm Selecting previously unselected package python3-psutil.
(Reading database ... 69023 files and directories currently installed.)
2018-11-14 18:41:21 DEBUG upgrade-charm Preparing to unpack .../python3-psutil_5.4.2-1_amd64.deb ...
2018-11-14 18:41:21 DEBUG upgrade-charm Unpacking python3-psutil (5.4.2-1) ...
2018-11-14 18:41:21 DEBUG upgrade-charm Setting up python3-psutil (5.4.2-1) ...
2018-11-14 18:41:23 DEBUG upgrade-charm Traceback (most recent call last):
2018-11-14 18:41:23 DEBUG upgrade-charm File "/var/lib/juju/agents/unit-swift-storage-z1-0/charm/hooks/upgrade-charm", line 114, in <module>
2018-11-14 18:41:23 DEBUG upgrade-charm from distutils.dir_util import mkpath
2018-11-14 18:41:23 DEBUG upgrade-charm ModuleNotFoundError: No module named 'distutils.dir_util'
2018-11-14 18:41:23 ERROR juju.worker.uniter.operation runhook.go:129 hook "upgrade-charm" failed: exit status 1

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/618013

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/618013
Committed: https://git.openstack.org/cgit/openstack/charm-swift-storage/commit/?id=3066151e774af396ae1c0c50bfbe5127692623e5
Submitter: Zuul
Branch: master

commit 3066151e774af396ae1c0c50bfbe5127692623e5
Author: Liam Young <email address hidden>
Date: Wed Nov 14 19:27:57 2018 +0000

    Install prerequisite packages on charm upgrade.

    When upgrading the charm some package dependancies are missing
    such as python3-distutils. This patch uses the same approach as the
    install hook to install packages before calling the the main python
    hook code.

    Change-Id: If3bfa6efd5a3924f3ca6d1309f82c3867cfd4c67
    Closes-Bug: #1803418