Ceph

When trying to upgrade from Mimic to Nautilus, the clients on the Mimic nodes fail to talk to the monitor cluster as soon as the first unit is upgraded:

1. ceph -s
   Traceback (most recent call last):
   File "/usr/bin/ceph", line 1241, in <module>
   retval = main()
   File "/usr/bin/ceph", line 1165, in main
   sigdict = parse_json_funcsigs(outbuf.decode('utf-8'), 'cli')
   File "/usr/lib/python3/dist-packages/ceph_argparse.py", line 788, in parse_json_funcsigs
   cmd['sig'] = parse_funcsig(cmd['sig'])
   File "/usr/lib/python3/dist-packages/ceph_argparse.py", line 728, in parse_funcsig
   raise JsonFormat(s)
   ceph_argparse.JsonFormat: unknown type CephBool

The monitor cluster is actually still functional according to that same command on the newly Nautilus unit:

1. ceph -s
   cluster:
   id: 2734983c-c88f-11e9-b6f9-fa163e8108c2
   health: HEALTH_OK

   services:
   mon: 3 daemons, quorum juju-a792f2-ceph-mimic-upgrade-0,juju-a792f2-ceph-mimic-upgrade-1,juju-a792f2-ceph-mimic-upgrade-2 (age 3m)
   mgr: juju-a792f2-ceph-mimic-upgrade-0(active), standbys: juju-a792f2-ceph-mimic-upgrade-1, juju-a792f2-ceph-mimic-upgrade-2
   osd: 3 osds: 3 up, 3 in
   rgw: 1 daemon active (juju-a792f2-ceph-mimic-upgrade-6)

   data:
   pools: 15 pools, 46 pgs
   objects: 187 objects, 1.1 KiB
   usage: 3.0 GiB used, 27 GiB / 30 GiB avail
   pgs: 46 active+clean