AttributeError: 'NoneType' object has no attribute 'failed'

[dpkp]

Via #1315 comments:

Traceback (most recent call last):
  File "./client_staging.py", line 53, in <module>
    results = consumer.poll(timeout_ms=10000, max_records=1)
  File "/usr/local/lib/python2.7/dist-packages/kafka/consumer/group.py", line 601, in poll
    records = self._poll_once(remaining, max_records)
  File "/usr/local/lib/python2.7/dist-packages/kafka/consumer/group.py", line 621, in _poll_once
    self._coordinator.poll()
  File "/usr/local/lib/python2.7/dist-packages/kafka/coordinator/consumer.py", line 271, in poll
    self.ensure_active_group()
  File "/usr/local/lib/python2.7/dist-packages/kafka/coordinator/base.py", line 401, in ensure_active_group
    if future.failed():
AttributeError: 'NoneType' object has no attribute 'failed'