Error on smtp-faker test

[vadim-su]

ERROR:asyncio:Task exception was never retrieved
future: <Task finished coro=<MessageHandler.msg_received() done, defined at /home/vagrant/src/smtp_faker/smtpd.py:33> exception=RuntimeError('Task got bad yield: <aiohttp_traversal.traversal.Traverser object at 0x7f2d81a3c7f0>',)>
Traceback (most recent call last):
  File "/usr/lib/python3.5/asyncio/tasks.py", line 241, in _step
    result = coro.throw(exc)
  File "/home/vagrant/src/smtp_faker/smtpd.py", line 35, in msg_received
    root = yield from self.app.get_root()
RuntimeError: Task got bad yield: <aiohttp_traversal.traversal.Traverser object at 0x7f2d81a3c7f0>

[zzzsochi]

Fixed in c7e21e7.