Remove unused skip_double_compressed_messages

This `skip_double_compressed_messages` flag was added in #755 in
order to fix #718.

However, grep'ing through the code, it looks like it this is no longer
used anywhere and doesn't do anything.

So removing it.

Author: jeffwidman

kafka/consumer/fetcher.py

@@ -55,7 +55,6 @@ class Fetcher(six.Iterator):
         'max_partition_fetch_bytes': 1048576,
         'max_poll_records': sys.maxsize,
         'check_crcs': True,
-        'skip_double_compressed_messages': False,
         'iterator_refetch_records': 1,  # undocumented -- interface may change
         'metric_group_prefix': 'consumer',
         'api_version': (0, 8, 0),
@@ -98,13 +97,6 @@ def __init__(self, client, subscriptions, metrics, **configs):
                 consumed. This ensures no on-the-wire or on-disk corruption to
                 the messages occurred. This check adds some overhead, so it may
                 be disabled in cases seeking extreme performance. Default: True
-            skip_double_compressed_messages (bool): A bug in KafkaProducer
-                caused some messages to be corrupted via double-compression.
-                By default, the fetcher will return the messages as a compressed
-                blob of bytes with a single offset, i.e. how the message was
-                actually published to the cluster. If you prefer to have the
-                fetcher automatically detect corrupt messages and skip them,
-                set this option to True. Default: False.
         """
         self.config = copy.copy(self.DEFAULT_CONFIG)
         for key in self.config:

kafka/consumer/group.py

@@ -165,13 +165,6 @@ class KafkaConsumer(six.Iterator):
         consumer_timeout_ms (int): number of milliseconds to block during
             message iteration before raising StopIteration (i.e., ending the
             iterator). Default block forever [float('inf')].
-        skip_double_compressed_messages (bool): A bug in KafkaProducer <= 1.2.4
-            caused some messages to be corrupted via double-compression.
-            By default, the fetcher will return these messages as a compressed
-            blob of bytes with a single offset, i.e. how the message was
-            actually published to the cluster. If you prefer to have the
-            fetcher automatically detect corrupt messages and skip them,
-            set this option to True. Default: False.
         security_protocol (str): Protocol used to communicate with brokers.
             Valid values are: PLAINTEXT, SSL. Default: PLAINTEXT.
         ssl_context (ssl.SSLContext): Pre-configured SSLContext for wrapping
@@ -279,7 +272,6 @@ class KafkaConsumer(six.Iterator):
         'sock_chunk_bytes': 4096,  # undocumented experimental option
         'sock_chunk_buffer_count': 1000,  # undocumented experimental option
         'consumer_timeout_ms': float('inf'),
-        'skip_double_compressed_messages': False,
         'security_protocol': 'PLAINTEXT',
         'ssl_context': None,
         'ssl_check_hostname': True,