fix to #965

[mushkevych]

fix to #965

[mushkevych]

Tests have failed due to

Traceback (most recent call last):
  File "/opt/python/3.6.7/lib/python3.6/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/opt/python/3.6.7/lib/python3.6/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/home/travis/build/Parsely/pykafka/pykafka/test/kafka_instance.py", line 570, in <module>
    bin_dir=args.download_dir)
  File "/home/travis/build/Parsely/pykafka/pykafka/test/kafka_instance.py", line 166, in __init__
    ManagedInstance.__init__(self, name, use_gevent=use_gevent)
  File "/home/travis/virtualenv/python3.6.7/lib/python3.6/site-packages/testinstances/managed_instance.py", line 63, in __init__
    self._start_process()
  File "/home/travis/build/Parsely/pykafka/pykafka/test/kafka_instance.py", line 278, in _start_process
    raise ProcessNotStartingError('Unable to start Kafka cluster.')
testinstances.exceptions.ProcessNotStartingError: Unable to start Kafka cluster.

[mushkevych]

Hi @emmett9001 I was wondering how can I help with reviewing this PR? It seems as the testing pipeline is failing inability to start Kafka test cluster.