Explicit tox_extra_args in zuul-jobs-test-tox

In change Iafeb88eaf9a596603ad4d2134a4574345d5189ab we fixed a bug
with handling of `tox --showconfig -vv` in the siblings tasks for
the tox role. This arose because of the desire to add tox_extra_args
to all tox invocations in Ibfe77f67e43135ae5af7588d6859b8b3dbd4c3ca
because we currently set a default of '-vv' for the tox_extra_args
rolevar. This fix could easily regress in the future if we were to
ever change the default value, so explicitly test with it in the
zuul-jobs-test-tox job by adding it to the python/tox test playbook.

Change-Id: Ib6ddf7d188904193a5ecd520acac1d676e5d78ae

test-playbooks/python/tox.yaml

@@ -11,6 +11,8 @@
       vars:
         tox_envlist: docs
         tox_constraints_file: '{{ zuul.project.src_dir }}/zuul-tests.d/test-constraints.txt'
+        # Make sure we test with verbose output even if the default changes
+        tox_extra_args: '-vv'
 
     - name: Run tox with multiple testenvs
       include_role:
@@ -19,6 +21,8 @@
         tox_envlist: docs,linters
         tox_environment:
           ANSIBLE_ROLES_PATH: "{{ ansible_user_dir }}/{{ zuul.project.src_dir }}/roles"
+        # Make sure we test with verbose output even if the default changes
+        tox_extra_args: '-vv'
 
     - name: Create tempfile to verify testenvs ran
       tempfile:
@@ -78,3 +82,5 @@
       vars:
         zuul_work_dir: "{{ zuul.project.src_dir }}/test-playbooks/python/"
         tox_envlist: '%s'
+        # Make sure we test with verbose output even if the default changes
+        tox_extra_args: '-vv'