Ensure that the zuul home can be traversed

The default permissions for the zuul home directory
are not the same in the various distributions.
As /home/zuul contains the sources, a 700 default may be
problematic when accessing those files, so make sure
that the executable permissions are set.

Closes-Bug: 1846251
Change-Id: Ic9769e56274d7205844b86d3b5200a6415e4acad

playbooks/pre.yaml

@@ -1,5 +1,12 @@
 - hosts: all
   pre_tasks:
+    - name: Fix the permissions of the zuul home directory
+      # Make sure that the zuul home can be traversed,
+      # so that all users can access the sources placed there.
+      # Some distributions create it with 700 by default.
+      file:
+        path: "{{ ansible_user_dir }}"
+        mode: a+x
     - name: Gather minimum local MTU
       set_fact:
         local_mtu: >