assess-status hook can error out due to juju failure

[Alex Kavanagh]

In theory, assess status ought not really to error out for any reason:

tracer: cleared flag run-default-update-status
tracer: -- dequeue handler reactive/layer_openstack.py:88:run_default_update_status
2020-09-28 12:27:54 INFO juju-log Invoking reactive handler: hooks/relations/mysql-innodb-cluster/peers.py:69:joined:cluster
2020-09-28 12:27:54 INFO juju-log Invoking reactive handler: hooks/relations/mysql-innodb-cluster/peers.py:75:changed:cluster
2020-09-28 12:27:55 INFO juju-log Invoking reactive handler: hooks/relations/tls-certificates/requires.py:109:broken:certificates
2020-09-28 12:27:55 INFO juju-log Invoking reactive handler: hooks/relations/mysql-router/provides.py:47:joined:db-router
2020-09-28 12:27:55 INFO juju-log Invoking reactive handler: hooks/relations/mysql-router/provides.py:53:changed:db-router
2020-09-28 12:27:56 DEBUG juju-log Running _assess_status()
2020-09-28 12:29:56 DEBUG update-status ERROR cannot set status: read tcp 172.17.112.11:48266->172.17.112.11:37017: i/o timeout
2020-09-28 12:29:56 DEBUG update-status Traceback (most recent call last):
2020-09-28 12:29:56 DEBUG update-status File "/var/lib/juju/agents/unit-mysql-innodb-cluster-2/charm/hooks/update-status", line 22, in <module>
2020-09-28 12:29:56 DEBUG update-status main()
2020-09-28 12:29:56 DEBUG update-status File "/var/lib/juju/agents/unit-mysql-innodb-cluster-2/.venv/lib/python3.8/site-packages/charms/reactive/__init__.py", line 84, in main
2020-09-28 12:29:56 DEBUG update-status hookenv._run_atexit()
2020-09-28 12:29:56 DEBUG update-status File "/var/lib/juju/agents/unit-mysql-innodb-cluster-2/.venv/lib/python3.8/site-packages/charmhelpers/core/hookenv.py", line 1343, in _run_atexit
2020-09-28 12:29:56 DEBUG update-status callback(*args, **kwargs)
2020-09-28 12:29:56 DEBUG update-status File "/var/lib/juju/agents/unit-mysql-innodb-cluster-2/.venv/lib/python3.8/site-packages/charms_openstack/charm/core.py", line 1219, in atexit_assess_status
2020-09-28 12:29:56 DEBUG update-status self._assess_status()
2020-09-28 12:29:56 DEBUG update-status File "lib/charm/openstack/mysql_innodb_cluster.py", line 1287, in _assess_status
2020-09-28 12:29:56 DEBUG update-status ch_core.hookenv.application_version_set(self.application_version)
2020-09-28 12:29:56 DEBUG update-status File "/var/lib/juju/agents/unit-mysql-innodb-cluster-2/.venv/lib/python3.8/site-packages/charmhelpers/core/hookenv.py", line 1184, in application_version_set
2020-09-28 12:29:56 DEBUG update-status subprocess.check_call(cmd)
2020-09-28 12:29:56 DEBUG update-status File "/usr/lib/python3.8/subprocess.py", line 364, in check_call
2020-09-28 12:29:56 DEBUG update-status raise CalledProcessError(retcode, cmd)
2020-09-28 12:29:56 DEBUG update-status subprocess.CalledProcessError: Command '['application-version-set', '8.0.21']' returned non-zero exit status 1.
2020-09-28 12:29:56 ERROR juju.worker.uniter.operation runhook.go:132 hook "update-status" failed: exit status 1