Comment 4 for bug 2011605

This upgrade run is also interesting: https://oil-jenkins.canonical.com/job/fce_openstackupgrade/20019//consoleFull

The innodb-cluster successfully upgrades and the charms look healthy, but then ceph-mon/0 throws this error when it tries to upgrade:

```
Traceback (most recent call last):
  File "./src/charm.py", line 282, in <module>
    main(CephMonCharm)
  File "/var/lib/juju/agents/unit-ceph-mon-0/charm/venv/ops/main.py", line 436, in main
    _emit_charm_event(charm, dispatcher.event_name)
  File "/var/lib/juju/agents/unit-ceph-mon-0/charm/venv/ops/main.py", line 144, in _emit_charm_event
    event_to_emit.emit(*args, **kwargs)
  File "/var/lib/juju/agents/unit-ceph-mon-0/charm/venv/ops/framework.py", line 354, in emit
    framework._emit(event)
  File "/var/lib/juju/agents/unit-ceph-mon-0/charm/venv/ops/framework.py", line 830, in _emit
    self._reemit(event_path)
  File "/var/lib/juju/agents/unit-ceph-mon-0/charm/venv/ops/framework.py", line 919, in _reemit
    custom_handler(event)
  File "./src/charm.py", line 85, in on_pre_series_upgrade
    hooks.pre_series_upgrade()
  File "/var/lib/juju/agents/unit-ceph-mon-0/charm/src/ceph_hooks.py", line 1218, in pre_series_upgrade
    set_unit_paused()
  File "/var/lib/juju/agents/unit-ceph-mon-0/charm/venv/charmhelpers/contrib/openstack/utils.py", line 1561, in set_unit_paused
    with unitdata.HookData()() as t:
  File "/var/lib/juju/agents/unit-ceph-mon-0/charm/venv/charmhelpers/core/unitdata.py", line 464, in __init__
    self.kv = kv()
  File "/var/lib/juju/agents/unit-ceph-mon-0/charm/venv/charmhelpers/core/unitdata.py", line 525, in kv
    _KV = Storage()
  File "/var/lib/juju/agents/unit-ceph-mon-0/charm/venv/charmhelpers/core/unitdata.py", line 190, in __init__
    self._init()
  File "/var/lib/juju/agents/unit-ceph-mon-0/charm/venv/charmhelpers/core/unitdata.py", line 385, in _init
    self.cursor.execute('''
sqlite3.OperationalError: database is locked
```

The crashdumps for this run are here:
https://oil-jenkins.canonical.com/artifacts/287f98ed-f8fa-4868-a664-0e9dc1b27f44/index.html