If virtualenv is broken, force re-install it

The virtualenv_support folder missing from the repo
container when upgrading due to the implementation
in the repo_build role which removes it. In order
to prevent breaking the virtualenv tooling, [1] is
being submitted. However, we still need to handle
the situation where the upgrade is done from a
version before that patch is implemented.

This patch implements a force-reinstallation of
virtualenv if the folder is missing.

[1] https://review.openstack.org/540351

Change-Id: I2dcfa1abb46ee4e088dac7c9e77e9772ba8a269e
Closes-Bug: #1746935

tasks/repo_install.yml

@@ -24,10 +24,29 @@
   retries: 5
   delay: 5
 
+# TODO(odyssey4me):
+# The following two tasks only applies to Pike->Queens upgrades,
+# so they can be removed in Rocky. See:
+# https://bugs.launchpad.net/openstack-ansible/+bug/1746935
+- name: List the current virtualenv_support folders in dist/site-packages
+  find:
+    file_type: any
+    patterns: "virtualenv_support"
+    paths:
+      - "/usr/local/lib/python2.7/dist-packages"
+      - "/usr/local/lib/python2.7/site-packages"
+  register: _virtualenv_support
+
+# TODO(odyssey4me):
+# We force a reinstall of the required pip packages when the
+# virtualenv_support folder is absent. This is to ensure that
+# we're able to create the venv properly for pypiserver.
+# The state ternary filter can be removed in Rocky as this is
+# only required for Pike->Queens upgrades.
 - name: Install required pip packages
   pip:
     name: "{{ repo_requires_pip_packages }}"
-    state: "{{ repo_server_pip_package_state }}"
+    state: "{{ (_virtualenv_support['matched'] | int > 0) | ternary(repo_server_pip_package_state, 'forcereinstall') }}"
     extra_args: >-
       {{ (pip_install_upper_constraints is defined) | ternary('--constraint ' + pip_install_upper_constraints | default(''),'') }}
       {{ pip_install_options | default('') }}