allmydata.test.cli.test_invite.Invite.test_invite_success is broken on Python 3.6

[sajith]

Per ​CircleCI, running master:

test_invite_success - allmydata.test.cli.test_invite.Invite

Traceback (most recent call last):
testtools.testresult.real._StringException: Traceback (most recent call last):
  File "/tmp/tahoe-lafs.tox/py36/lib/python3.6/site-packages/twisted/internet/defer.py", line 1445, in _inlineCallbacks
    result = current_context.run(g.send, result)
  File "/tmp/tahoe-lafs.tox/py36/lib/python3.6/site-packages/contextvars/__init__.py", line 38, in run
    return callable(*args, **kwargs)
  File "/tmp/tahoe-lafs.tox/py36/lib/python3.6/site-packages/allmydata/test/cli/test_invite.py", line 238, in test_invite_success
    b"--shares-total", b"3",
  File "/tmp/tahoe-lafs.tox/py36/lib/python3.6/site-packages/allmydata/test/cli/test_invite.py", line 204, in _invite_success
    *(extra_args + ("foo",))
  File "/tmp/tahoe-lafs.tox/py36/lib/python3.6/site-packages/allmydata/test/common_util.py", line 92, in run_cli_native
    nodeargs=nodeargs,
  File "/tmp/tahoe-lafs.tox/py36/lib/python3.6/site-packages/pyutil/assertutil.py", line 35, in precondition
    raise AssertionError(_format_error("precondition", args, kwargs))
AssertionError: precondition: "arguments to run_cli must be <class 'str'> -- convert using unicode_to_argv" <class 'str'>, 'args': ['allmydata.test.cli.test_invite/Invite/test_invite_success/ul8ugiiz/temp/introducer', 'invite', b'--shares-needed', b'1', b'--shares-happy', b'2', ...] <class 'list'>, 'nodeargs': [] <class 'list'>, 'verb': '-d' <class 'str'>

Not sure why CI did not catch that earlier on.

[GitHub <noreply@…>]

In 3653b289/trunk:

Merge pull request #1022 from tahoe-lafs/3654.test-invite-success-py36

Make test_invite_success pass on Python 3.6

Fixes: ticket:3654