Fix docker-credential-helpers error in gate

Without pass package installed, docker-docker-credential-helpers drops
the following error message on running docker build:

the free(): invalid pointer
SIGABRT: abort
...

GitHub issue #103 in docker/docker-credential-helpers.
Ubuntu Launchpad Bug #1813003.

Change-Id: I9d3ff4773736a784cef16611453d4f4d47a34187

.zuul.yaml

@@ -31,17 +31,6 @@
     post-run: playbooks/airship-collect-logs.yaml
     nodeset: airship-images-single-node
 
-- job:
-    name: images-upload-git-mirror
-    parent: upload-git-mirror
-    description: Mirrors airship/images to airshipit/images
-    vars:
-      git_mirror_repository: airshipit/images
-    secrets:
-      - name: git_mirror_credentials
-        secret: images_airshipit_github_secret
-        pass-to-parent: true
-
 - job:
     name: airship-images-build
     nodeset: airship-images-single-node
@@ -60,6 +49,17 @@
       - name: airship_images_quay_creds
         secret: airship_images_quay_creds
 
+- job:
+    name: images-upload-git-mirror
+    parent: upload-git-mirror
+    description: Mirrors airship/images to airshipit/images
+    vars:
+      git_mirror_repository: airshipit/images
+    secrets:
+      - name: git_mirror_credentials
+        secret: images_airshipit_github_secret
+        pass-to-parent: true
+
 - nodeset:
     name: airship-images-single-node
     nodes:

playbooks/airship-images-build.yaml

@@ -18,8 +18,9 @@
     - name: Install python-docker module
       apt:
         pkg:
-        - python-docker
-        - python3-requests
+          - python-docker
+          - python3-requests
+          - pass
         state: present
       become: true
       when: ansible_distribution == 'Debian' or ansible_distribution == 'Ubuntu'