[bionic-stein] test_104_compute_api_functionality occasionally fails by getting an HTTP500 when listing flavors using nova client

[Aurelien Lourot]

Seen here:
https://review.opendev.org/c/openstack/charm-nova-cloud-controller/+/809281
https://openstack-ci-reports.ubuntu.com/artifacts/d84/809281/5/check/bionic-stein/d84251d/job-output.txt

ERROR: test_104_compute_api_functionality (zaza.openstack.charm_tests.nova.tests.NovaCloudController)
Verify basic compute API functionality.
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/ubuntu/src/review.opendev.org/openstack/charm-nova-cloud-controller/.tox/func-target/lib/python3.6/site-packages/zaza/openstack/charm_tests/nova/tests.py", line 523, in test_104_compute_api_functionality
    assert(len(nova.flavors.list()) > 0)
  File "/home/ubuntu/src/review.opendev.org/openstack/charm-nova-cloud-controller/.tox/func-target/lib/python3.6/site-packages/novaclient/v2/flavors.py", line 148, in list
    return self._list("/flavors%s" % detail, "flavors", filters=qparams)
  File "/home/ubuntu/src/review.opendev.org/openstack/charm-nova-cloud-controller/.tox/func-target/lib/python3.6/site-packages/novaclient/base.py", line 254, in _list
    resp, body = self.api.client.get(url)
  File "/home/ubuntu/src/review.opendev.org/openstack/charm-nova-cloud-controller/.tox/func-target/lib/python3.6/site-packages/keystoneauth1/adapter.py", line 395, in get
    return self.request(url, 'GET', **kwargs)
  File "/home/ubuntu/src/review.opendev.org/openstack/charm-nova-cloud-controller/.tox/func-target/lib/python3.6/site-packages/novaclient/client.py", line 78, in request
    raise exceptions.from_response(resp, body, url, method)
novaclient.exceptions.ClientException: Unknown Error (HTTP 500)

[Corey Bryant (corey.bryant)]

I took a look through some recent gerrit reviews and it does seem that this is limited to the bionic-stein tests and it is a periodic failure, so I will triage this as Low for now.