--exclude-device-files and --exclude-other-filesystems options crashes

Quack,

I'm using duplicity 0.8.04-2 on Debian unstable (Python 3.7.4).

Recently I got:
Traceback (innermost last):
  File "/usr/bin/duplicity", line 107, in <module>
    with_tempdir(main)
  File "/usr/bin/duplicity", line 93, in with_tempdir
    fn()
  File "/usr/lib/python3/dist-packages/duplicity/dup_main.py", line 1522, in main
    action = commandline.ProcessCommandLine(sys.argv[1:])
  File "/usr/lib/python3/dist-packages/duplicity/commandline.py", line 1166, in ProcessCommandLine
    args = parse_cmdline_options(cmdline_list)
  File "/usr/lib/python3/dist-packages/duplicity/commandline.py", line 684, in parse_cmdline_options
    (options, args) = parser.parse_args(arglist)
  File "/usr/lib/python3.7/optparse.py", line 1387, in parse_args
    stop = self._process_args(largs, rargs, values)
  File "/usr/lib/python3.7/optparse.py", line 1427, in _process_args
    self._process_long_opt(rargs, values)
  File "/usr/lib/python3.7/optparse.py", line 1501, in _process_long_opt
    option.process(opt, value, values, self)
  File "/usr/lib/python3.7/optparse.py", line 785, in process
    self.action, self.dest, opt, value, values, parser)
  File "/usr/lib/python3/dist-packages/duplicity/commandline.py", line 203, in take_action
    self, action, dest, opt, value, values, parser)
  File "/usr/lib/python3.7/optparse.py", line 805, in take_action
    self.callback(self, opt, value, parser, *args, **kwargs)
  File "/usr/lib/python3/dist-packages/duplicity/commandline.py", line 262, in add_selection
    select_opts.append((util.fsdecode(option), util.fsdecode(additional_arg)))
  File "/usr/lib/python3.7/os.py", line 821, in fsdecode
    filename = fspath(filename) # Does type-checking of `filename`.
 TypeError: expected str, bytes or os.PathLike object, not NoneType

Printing the `option` variable I got --exclude-device-files and --exclude-other-filesystems. As they do not take arguments I guess they should not use the `add_selection` callback but I'm not sure what it should do instead so I cannot provide a patch yet. Seems `ParseArgs()` is parsing options again, so maybe nothing is needed at this stage.

\_o<