The virtualenv and executable parameters are exclusive.

Previous versions of ansible did not have the errorcatching capabilities to catch this.

playbooks/roles/jenkins_worker/tasks/python_platform_worker.yml

@@ -26,7 +26,6 @@
     extra_args: "--exists-action=w"
     virtualenv: "{{ jenkins_home }}/edx-venv"
     virtualenv_command: virtualenv
-    executable: pip
   with_items:
     - pre.txt
     - github.txt
@@ -49,7 +48,6 @@
     extra_args: "--exists-action=w"
     virtualenv: "{{ jenkins_home }}/edx-venv"
     virtualenv_command: virtualenv
-    executable: pip
   with_items:
     - post.txt
   become_user: "{{ jenkins_user }}"