Move docker image pulling for wheel buidler to pre-run (#5645)

.zuul.d/jobs.yaml

@@ -29,6 +29,7 @@
 - job:
     name: pyca-cryptography-build-wheel
     abstract: true
+    pre-run: .zuul.playbooks/playbooks/wheel/pre.yaml
     run: .zuul.playbooks/playbooks/wheel/main.yaml
 
 - job:

.zuul.playbooks/playbooks/wheel/pre.yaml

@@ -0,0 +1,42 @@
+- hosts: all
+  tasks:
+    - name: Sanity check build list
+      assert:
+        that: wheel_builds is defined
+
+    - name: Run ensure-docker
+      include_role:
+        name: ensure-docker
+
+    - name: Workaround Linaro aarch64 cloud MTU issues
+      # NOTE(ianw) : Docker default networking, the Linaro NAT setup and
+      # *insert random things here* cause PMTU issues, resulting in hung
+      # connections, particularly to fastly CDN (particularly annoying
+      # because pypi and pythonhosted live behind that).  Can remove after
+      # upstream changes merge, or we otherwise find a solution in the
+      # upstream cloud.
+      #  https://review.opendev.org/747062
+      #  https://review.opendev.org/746833
+      #  https://review.opendev.org/747064
+      when: ansible_architecture == 'aarch64'
+      block:
+        - name: Install jq
+          package:
+            name: jq
+            state: present
+          become: yes
+
+        - name: Reset docker MTU
+          shell: |
+              jq --arg mtu 1400 '. + {mtu: $mtu|tonumber}' /etc/docker/daemon.json > /etc/docker/daemon.json.new
+              cat /etc/docker/daemon.json.new
+              mv /etc/docker/daemon.json.new /etc/docker/daemon.json
+              service docker restart
+          become: yes
+
+    - name: Pre-pull containers
+      command: >-
+        docker pull {{ item.image }}
+      become: yes
+      loop: '{{ wheel_builds }}'
+

.zuul.playbooks/playbooks/wheel/roles/build-wheel-manylinux/tasks/main.yaml

@@ -11,36 +11,6 @@
   include_role:
     name: ensure-pip
 
-- name: Run ensure-docker
-  include_role:
-    name: ensure-docker
-
-- name: Workaround Linaro aarch64 cloud MTU issues
-  # NOTE(ianw) : Docker default networking, the Linaro NAT setup and
-  # *insert random things here* cause PMTU issues, resulting in hung
-  # connections, particularly to fastly CDN (particularly annoying
-  # because pypi and pythonhosted live behind that).  Can remove after
-  # upstream changes merge, or we otherwise find a solution in the
-  # upstream cloud.
-  #  https://review.opendev.org/747062
-  #  https://review.opendev.org/746833
-  #  https://review.opendev.org/747064
-  when: ansible_architecture == 'aarch64'
-  block:
-    - name: Install jq
-      package:
-        name: jq
-        state: present
-      become: yes
-
-    - name: Reset docker MTU
-      shell: |
-          jq --arg mtu 1400 '. + {mtu: $mtu|tonumber}' /etc/docker/daemon.json > /etc/docker/daemon.json.new
-          cat /etc/docker/daemon.json.new
-          mv /etc/docker/daemon.json.new /etc/docker/daemon.json
-          service docker restart
-      become: yes
-
 # We build an sdist of the checkout, and then build wheels from the
 # sdist.  This ensures that nothing is left out of the sdist.
 - name: Install sdist required packages
@@ -95,12 +65,6 @@
     dest: '{{ _build_dir }}'
     mode: 0755
 
-- name: Pre-pull containers
-  command: >-
-    docker pull {{ item.image }}
-  become: yes
-  loop: '{{ wheel_builds }}'
-
 - name: Run builds
   command: |
     docker run --rm \