test_010_wait_for_image_sync consistently fails

[Aurelien Lourot]

ERROR: test_010_wait_for_image_sync (zaza.openstack.charm_tests.glance_simplestreams_sync.tests.GlanceSimpleStreamsSyncTest)
Wait for images to be synced. Expect at least four.
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/tmp/tmp.Rdt1C5sZDN/func-smoke/lib/python3.5/site-packages/zaza/openstack/charm_tests/glance_simplestreams_sync/tests.py", line 65, in test_010_wait_for_image_sync
    self.assertTrue(retry_image_sync(self.glance_client))
  File "/tmp/tmp.Rdt1C5sZDN/func-smoke/lib/python3.5/site-packages/tenacity/__init__.py", line 333, in wrapped_f
    return self(f, *args, **kw)
  File "/tmp/tmp.Rdt1C5sZDN/func-smoke/lib/python3.5/site-packages/tenacity/__init__.py", line 423, in __call__
    do = self.iter(retry_state=retry_state)
  File "/tmp/tmp.Rdt1C5sZDN/func-smoke/lib/python3.5/site-packages/tenacity/__init__.py", line 373, in iter
    six.raise_from(retry_exc, fut.exception())
  File "<string>", line 3, in raise_from
tenacity.RetryError: RetryError[<Future at 0x7fca934be2b0 state=finished returned list>]

https://review.opendev.org/c/openstack/charm-glance-simplestreams-sync/+/770387
https://openstack-ci-reports.ubuntu.com/artifacts/test_charm_pipeline_func_smoke/openstack/charm-glance-simplestreams-sync/770387/1/21147/index.html

https://review.opendev.org/c/openstack/charm-glance-simplestreams-sync/+/771017
https://openstack-ci-reports.ubuntu.com/artifacts/test_charm_pipeline_func_smoke/openstack/charm-glance-simplestreams-sync/771017/1/21191/index.html

[Aurelien Lourot (aurelien-lourot)]

https://review.opendev.org/c/openstack/charm-glance-simplestreams-sync/+/771816