Split download container task for delegate and non-delegate modes (#2077)

Ansible cannot seem to handle omitting delegate_to since v2.4.0.0.

Possibly related: https://github.com/ansible/ansible/issues/30760

roles/download/tasks/download_container.yml

@@ -10,16 +10,31 @@
   tags:
     - facts
 
-- name: container_download | Download containers if pull is required or told to always pull
+# FIXME(mattymo): In Ansible 2.4 omitting download delegate is broken. Move back
+#                 to one task in the future.
+- name: container_download | Download containers if pull is required or told to always pull (delegate)
   command: "{{ docker_bin_dir }}/docker pull {{ pull_args }}"
   register: pull_task_result
   until: pull_task_result|succeeded
   retries: 4
   delay: "{{ retry_stagger | random + 3 }}"
   when:
+    - download_run_once
+    - download.enabled
+    - download.container
+    - pull_required|default(download_always_pull)
+  delegate_to: "{{ download_delegate }}"
+  delegate_facts: yes
+  run_once: yes
+
+- name: container_download | Download containers if pull is required or told to always pull (all nodes)
+  command: "{{ docker_bin_dir }}/docker pull {{ pull_args }}"
+  register: pull_task_result
+  until: pull_task_result|succeeded
+  retries: 4
+  delay: "{{ retry_stagger | random + 3 }}"
+  when:
+    - not download_run_once
     - download.enabled
     - download.container
     - pull_required|default(download_always_pull)
-  delegate_to: "{{ download_delegate if download_run_once or omit }}"
-  delegate_facts: no
-  run_once: "{{ download_run_once }}"