UnicodeEncodeError from logging code during ceph-volume lvm create

When deploying ceph-osd with Bionic-Stein, a UnicdeEncodeError exception is logged every time a disk is initialized as a BlueStore OSD. The logging framework appears to catch this and it does not cause any actual problems, only the spurious warning.

The issue appears to be due to non-ascii characters in the output from "systemctl enable" that is executed by ceph-volume (you can see the stderr output at the bottom of the message)

cmd: ['ceph-volume', 'lvm', 'create', '--osd-fsid', '234af60b-d880-4dbb-89dd-658b1412f360', '--bluestore', '--data', 'ceph-234af60b-d880-4dbb-89dd-658b1412f360/osd-block-234af60b-d880-4dbb-89dd-658b1412f360', '--block.db', 'ceph-db-efa085db-6b36-4370-b3fb-76ddd7873154/osd-db-234af60b-d880-4dbb-89dd-658b1412f360']

--- Logging error ---
Traceback (most recent call last):
  File "/usr/lib/python3.6/logging/__init__.py", line 996, in emit
    stream.write(msg)
UnicodeEncodeError: 'ascii' codec can't encode character '\u2192' in position 186: ordinal not in range(128)
Call stack:
  File "/usr/sbin/ceph-volume", line 11, in <module>
    load_entry_point('ceph-volume==1.0.0', 'console_scripts', 'ceph-volume')()
  File "/usr/lib/python3/dist-packages/ceph_volume/main.py", line 38, in __init__
    self.main(self.argv)
  File "/usr/lib/python3/dist-packages/ceph_volume/decorators.py", line 59, in newfunc
    return f(*a, **kw)
  File "/usr/lib/python3/dist-packages/ceph_volume/main.py", line 148, in main
    terminal.dispatch(self.mapper, subcommand_args)
  File "/usr/lib/python3/dist-packages/ceph_volume/terminal.py", line 188, in dispatch
    instance.main()
  File "/usr/lib/python3/dist-packages/ceph_volume/devices/lvm/main.py", line 40, in main
    terminal.dispatch(self.mapper, self.argv)
  File "/usr/lib/python3/dist-packages/ceph_volume/terminal.py", line 188, in dispatch
    instance.main()
  File "/usr/lib/python3/dist-packages/ceph_volume/devices/lvm/create.py", line 69, in main
    self.create(args)
  File "/usr/lib/python3/dist-packages/ceph_volume/decorators.py", line 16, in is_root
    return func(*a, **kw)
  File "/usr/lib/python3/dist-packages/ceph_volume/devices/lvm/create.py", line 32, in create
    Activate([]).activate(args)
  File "/usr/lib/python3/dist-packages/ceph_volume/decorators.py", line 16, in is_root
    return func(*a, **kw)
  File "/usr/lib/python3/dist-packages/ceph_volume/devices/lvm/activate.py", line 257, in activate
    activate_bluestore(lvs, no_systemd=args.no_systemd)
  File "/usr/lib/python3/dist-packages/ceph_volume/devices/lvm/activate.py", line 184, in activate_bluestore
    systemctl.enable_volume(osd_id, osd_fsid, 'lvm')
  File "/usr/lib/python3/dist-packages/ceph_volume/systemd/systemctl.py", line 59, in enable_volume
    return enable(volume_unit % (device_type, id_, fsid))
  File "/usr/lib/python3/dist-packages/ceph_volume/systemd/systemctl.py", line 19, in enable
    process.run(['systemctl', 'enable', unit])
  File "/usr/lib/python3/dist-packages/ceph_volume/process.py", line 137, in run
    log_descriptors(reads, process, terminal_logging)
  File "/usr/lib/python3/dist-packages/ceph_volume/process.py", line 59, in log_descriptors
    log_output(descriptor_name, message, terminal_logging, True)
  File "/usr/lib/python3/dist-packages/ceph_volume/process.py", line 34, in log_output
    logger.info(line)
Message: 'stderr Created symlink /<email address hidden> \u2192 /lib/systemd/system/ceph-volume@.service.'
Arguments: ()