Remove the virtualenv version check

Simplify this code by making the assumption that we always have a
new enough version of virtualenv present. Centos-7 ships 15.1.0 so
it is now possible to remove some conditional logic as well.

This patch removes the version check and replaces it with a check
that the virtualenv command is present on the system patch and
is usable.

Change-Id: I1a8f4961358c9551c5493b332187b411177b2769

tasks/python_venv_install.yml

@@ -50,7 +50,7 @@
 - name: Create the virtualenv (if it does not exist)
   command: >-
     virtualenv
-    {{ _venv_create_extra_options }}
+    --no-download
     --python={{ venv_python_executable }}
     {{ (ansible_pkg_mgr == 'apt') | ternary('--always-copy', '') }}
     {{ venv_install_destination_path }}

tasks/python_venv_preflight.yml

@@ -21,34 +21,15 @@
   when:
     - venv_install_destination_path is not defined
 
-- name: Collect the version of virtualenv from either stdout or stderr
-  shell: |
-    virtualenv --version 2>&1 || echo 'none'
-  args:
-    executable: /bin/bash
+- name: Check for virtualenv command being available on system path
+  command: 'which virtualenv'
+  register: virtualenv_installed
+  ignore_errors: yes
   changed_when: false
-  failed_when: false
-  register: _virtualenv_version
 
-  # _virtualenv_version may take two forms:
-  # (stdout) '15.1.0'
-  # (stderr) 'virtualenv 20.0.1 from /usr/local/lib/python2.7/dist-packages/virtualenv/__init__.pyc'
-- name: Extract just the virtualevn version number
-  set_fact:
-    _virtualenv_version_number: "{{ (_virtualenv_version.stdout.split(' ') | length == 1) | ternary(_virtualenv_version.stdout, _virtualenv_version.stdout.split(' ')[1]) }}"
-
-- name: Fail when required virtualenv version is not present
+- name: Fail when required virtualenv is not present
   fail:
     msg: >-
-      The required virtualenv version is not present.
-      The minimum version of 1.10 is required, but
-      {{ _virtualenv_version_number }} is installed.
+      The command 'virtualenv' version is not present.
   when:
-    - ((_virtualenv_version_number | trim) == 'none') or
-      ((_virtualenv_version_number | trim) is version('1.10', '<'))
-
-- name: Set extra virtualenv parameters
-  set_fact:
-    _venv_create_extra_options: >-
-      {{ ((_virtualenv_version_number | trim) is version('14.0.0', '<')) | ternary('--never-download', '--no-download') }}
-      {{ ((_virtualenv_version_number | trim) is version('1.7.0', '<')) | ternary('--no-site-packages', '') }}
+    virtualenv_installed.rc != 0

tasks/python_venv_wheel_build.yml

@@ -69,7 +69,7 @@
     - name: Create the wheel build virtualenv (if it does not exist)
       command: >-
         virtualenv
-        {{ _venv_create_extra_options }}
+        --no-download
         --python={{ venv_python_executable }}
         {{ (ansible_pkg_mgr == 'apt') | ternary('--always-copy', '') }}
         {{ venv_build_host_venv_path }}