Kafka

Bugfixes
* Fix bug causing KafkaProducer to double-compress message batches on retry
* Check for double-compressed messages in KafkaConsumer, log warning and optionally skip
* Drop recursion in _unpack_message_set; only decompress once

Bugfixes
* Update consumer_timeout_ms docstring - KafkaConsumer raises StopIteration, no longer ConsumerTimeout
* Use explicit subscription state flag to handle seek() during message iteration
* Fix consumer iteration on compacted topics (dpkp PR 752)
* Support ssl_password config when loading cert chains (amckemie PR 750)

Patch Improvements
* Fix gc error log: avoid AttributeError in _unregister_cleanup (dpkp PR 747)
* Wakeup socket optimizations (dpkp PR 740)
* Assert will be disabled by "python -O" (tyronecai PR 736)
* Randomize order of topics/partitions processed by fetcher to improve balance (dpkp PR 732)
* Allow client.check_version timeout to be set in Producer and Consumer constructors (eastlondoner PR 647)

Bugfixes
* Clarify timeout unit in KafkaProducer close and flush (ms7s PR 734)
* Avoid busy poll during metadata refresh failure with retry_backoff_ms (dpkp PR 733)
* Check_version should scan nodes until version found or timeout (dpkp PR 731)
* Fix bug which could cause least_loaded_node to always return the same unavailable node (dpkp PR 730)
* Fix producer garbage collection with weakref in atexit handler (dpkp PR 728)
* Close client selector to fix fd leak (msmith PR 729)
* Tweak spelling mistake in error const (steve8918 PR 719)
* Rearrange connection tests to separate legacy KafkaConnection

Bugfixes
* Fix regression in MessageSet decoding wrt PartialMessages (716)
* Catch response decode errors and log details (715)
* Fix Legacy support url (712 - JonasGroeger)
* Update sphinx docs re 0.10 broker support

This release officially adds support for Kafka 0.10
* Add protocol support for ApiVersionRequest (dpkp PR 678)
* KAFKA-3025: Message v1 -- add timetamp and relative offsets (dpkp PR 693)
* Use Fetch/Produce API v2 for brokers >= 0.10 (uses message format v1) (dpkp PR 694)
* Use standard LZ4 framing for v1 messages / kafka 0.10 (dpkp PR 695)

Consumers
* Update SimpleConsumer / legacy protocol to handle compressed messages (paulcavallaro PR 684)

Producers
* KAFKA-3388: Fix expiration of batches sitting in the accumulator (dpkp PR 699)
* KAFKA-3197: when max.in.flight.request.per.connection = 1, attempt to guarantee ordering (dpkp PR 698)
* Don't use soon-to-be-reserved keyword await as function name (FutureProduceResult) (dpkp PR 697)

Clients
* Fix socket leaks in KafkaClient (dpkp PR 696)

Documentation
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Internals
* Support SSL CRL [requires python 2.7.9+ / 3.4+] (vincentbernat PR 683)
* Use original hostname for SSL checks (vincentbernat PR 682)
* Always pass encoded message bytes to MessageSet.encode()
* Raise ValueError on protocol encode/decode errors
* Supplement socket.gaierror exception in BrokerConnection.connect() (erikbeebe PR 687)
* BrokerConnection check_version: expect 0.9 to fail with CorrelationIdError
* Fix small bug in Sensor (zackdever PR 679)