test_transport_set_to_sftp errors with 'staticmethod' object is not callable

git describe --tags
brz-3.3.4-880-g11663014fd

$ BRZ_PLUGIN_PATH=-site:-user python3 -m breezy selftest test_transport_set_to_sftp

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ERROR: breezy.tests.blackbox.test_selftest.TestOptions.test_transport_set_to_sftp
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Traceback (most recent call last):
testtools.testresult.real._StringException: log: {{{
0.001 run brz: ['selftest', '--transport=sftp']
0.001 breezy version: 3.4.0.dev
0.002 brz arguments: ['selftest', '--transport=sftp']
}}}

Traceback (most recent call last):
  File "/home/robertc/src/breezy/breezy/tests/blackbox/test_selftest.py", line 59, in test_transport_set_to_sftp
    params = self.get_params_passed_to_core('selftest --transport=sftp')
  File "/home/robertc/src/breezy/breezy/tests/blackbox/test_selftest.py", line 42, in get_params_passed_to_core
    self.run_bzr(cmdline)
  File "/home/robertc/src/breezy/breezy/tests/__init__.py", line 2061, in run_bzr
    result = self._run_bzr_core(
  File "/home/robertc/src/breezy/breezy/tests/__init__.py", line 1923, in _run_bzr_core
    result = self.apply_redirected(
  File "/home/robertc/src/breezy/breezy/tests/__init__.py", line 2364, in apply_redirected
    return a_callable(*args, **kwargs)
  File "/home/robertc/src/breezy/breezy/commands.py", line 1332, in run_bzr_catch_user_errors
    return run_bzr(argv)
  File "/home/robertc/src/breezy/breezy/commands.py", line 1221, in run_bzr
    ret = run(*run_argv)
  File "/home/robertc/src/breezy/breezy/commands.py", line 743, in run_argv_aliases
    args, opts = parse_args(self, argv, alias_argv)
  File "/home/robertc/src/breezy/breezy/commands.py", line 925, in parse_args
    options, args = parser.parse_args(args)
  File "/usr/lib/python3.9/optparse.py", line 1387, in parse_args
    stop = self._process_args(largs, rargs, values)
  File "/usr/lib/python3.9/optparse.py", line 1427, in _process_args
    self._process_long_opt(rargs, values)
  File "/usr/lib/python3.9/optparse.py", line 1501, in _process_long_opt
    option.process(opt, value, values, self)
  File "/usr/lib/python3.9/optparse.py", line 784, in process
    return self.take_action(
  File "/usr/lib/python3.9/optparse.py", line 805, in take_action
    self.callback(self, opt, value, parser, *args, **kwargs)
  File "/home/robertc/src/breezy/breezy/option.py", line 240, in _optparse_callback
    v = self.type(value)
TypeError: 'staticmethod' object is not callable

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Ran 1 test in 0.017s