Cannot uninstall 'six'

[Scott Tadman]

During the installation the following shows up in the Juju debug log:

unit-juju-gui-1: 01:18:39 INFO unit.juju-gui/1.juju-log Completing the installation.
unit-juju-gui-1: 01:18:39 INFO unit.juju-gui/1.juju-log >>> Entering prepare.py
unit-juju-gui-1: 01:18:39 INFO unit.juju-gui/1.juju-log Installing dependencies.
unit-juju-gui-1: 01:18:39 INFO unit.juju-gui/1.juju-log No missing deb packages.
unit-juju-gui-1: 01:18:40 INFO unit.juju-gui/1.juju-log Setting up base dir: /var/lib/juju-gui.
unit-juju-gui-1: 01:18:40 INFO unit.juju-gui/1.juju-log Installing juju gui.
unit-juju-gui-1: 01:18:40 INFO unit.juju-gui/1.juju-log Installing Juju GUI from /var/lib/juju/agents/unit-juju-gui-1/charm/releases/jujugui-2.2.4.tar.bz2.
unit-juju-gui-1: 01:18:49 INFO unit.juju-gui/1.juju-log Exception caught:
unit-juju-gui-1: 01:18:49 INFO unit.juju-gui/1.juju-log Looking in links: file:////var/lib/juju/agents/unit-juju-gui-1/charm/jujugui-deps
Processing ./releases/jujugui-2.2.4.tar.bz2
Requirement already satisfied: Mako==1.0.2 in /usr/local/lib/python2.7/dist-packages (from jujugui==2.2.4) (1.0.2)
Requirement already satisfied: MarkupSafe==0.23 in /usr/local/lib/python2.7/dist-packages (from jujugui==2.2.4) (0.23)
Collecting Paste==2.0.2 (from jujugui==2.2.4)
Collecting PasteDeploy==1.5.2 (from jujugui==2.2.4)
Collecting Pygments==2.0.2 (from jujugui==2.2.4)
Collecting WebOb==1.5.1 (from jujugui==2.2.4)
Requirement already satisfied: argparse==1.2.1 in /usr/lib/python2.7 (from jujugui==2.2.4) (1.2.1)
Collecting convoy==0.4.3 (from jujugui==2.2.4)
Collecting pyramid-mako==1.0.2 (from jujugui==2.2.4)
Collecting pyramid==1.5.7 (from jujugui==2.2.4)
Collecting repoze.lru==0.6 (from jujugui==2.2.4)
Collecting setuptools==21.1.0 (from jujugui==2.2.4)
Collecting six==1.10.0 (from jujugui==2.2.4)
Collecting translationstring==1.3 (from jujugui==2.2.4)
Collecting venusian==1.0 (from jujugui==2.2.4)
Collecting waitress==0.8.10 (from jujugui==2.2.4)
Requirement already satisfied: wsgiref==0.1.2 in /usr/lib/python2.7 (from jujugui==2.2.4) (0.1.2)
Collecting zope.deprecation==4.1.2 (from jujugui==2.2.4)
Collecting zope.interface==4.1.3 (from jujugui==2.2.4)
Building wheels for collected packages: jujugui
  Building wheel for jujugui (setup.py): started
  Building wheel for jujugui (setup.py): finished with status 'done'
  Stored in directory: /root/.cache/pip/wheels/9c/13/3b/998e357794695086640cac20a56052fec426c7b39fdc19c674
Successfully built jujugui
Installing collected packages: six, Paste, PasteDeploy, Pygments, WebOb, convoy, setuptools, zope.deprecation, repoze.lru, zope.interface, translationstring, venusian, pyramid, pyramid-mako, waitress, jujugui
  Found existing installation: six 1.5.2
DEPRECATION: Python 2.7 will reach the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 won't be maintained after that date. A future version of pip will drop support for Python 2.7.
launchpadlib 1.10.2 requires testresources, which is not installed.
Cannot uninstall 'six'. It is a distutils installed project and thus we cannot accurately determine which files belong to it which would lead to only a partial uninstall.

This ends up with the unit ending up in an error state: hook failed: "install"

[Scott Tadman (tadman)]

This can be fixed by dropping into a shell on the container and running:

    pip2 install --ignore-installed 'six==1.10.0'

Where that installs the correct version and everything's happy when it retries the installation.