Ensure the virtualenv is only created when it doesn't exist.

playbooks/roles/xqwatcher/tasks/code_jail.yml

@@ -15,6 +15,8 @@
 # Do this first so symlinks can be resolved in the next step
 - name: Create jail virtualenv
   shell: "/usr/local/bin/virtualenv --python={{ item.PYTHON_EXECUTABLE }} --no-site-packages {{ xqwatcher_app_dir }}/venvs/{{ item.QUEUE_CONFIG.HANDLERS[0].CODEJAIL.name }}"
+  args:
+    creates: "{{ xqwatcher_app_dir }}/venvs/{{ item.QUEUE_CONFIG.HANDLERS[0].CODEJAIL.name }}/bin/pip"
   with_items: "{{ XQWATCHER_COURSES }}"
   tags:
     - install