Fix a couple flake8 errors including a supposed PEP-8 violation that is

actually a PEP-8-suggested acceptable option of how to handle the
offending situation. =P

pulsar/client/amqp_exchange.py

@@ -105,7 +105,7 @@ class PulsarExchange(object):
                         # queue once before the ack manager starts doing its
                         # thing
                         if self.acks_enabled and queue_name.endswith(ACK_QUEUE_SUFFIX):
-                            ack_manager_thread = self.__start_ack_manager(queue_name)
+                            self.__start_ack_manager(queue_name)
                         while check and connection.connected:
                             try:
                                 connection.drain_events(timeout=self.__timeout)
@@ -184,7 +184,7 @@ class PulsarExchange(object):
         publish_log_prefix = self.__publish_log_prefex(transaction_uuid)
         log.debug("%sBegin publishing to key %s", publish_log_prefix, key)
         if (self.acks_enabled and not name.endswith(ACK_QUEUE_SUFFIX)
-            and ACK_FORCE_NOACK_KEY not in payload):
+                and ACK_FORCE_NOACK_KEY not in payload):
             # Publishing a message on a normal queue and it's not a republish
             # (or explicitly forced do-not-ack), so add ack keys
             ack_uuid = str(transaction_uuid)

pulsar/client/util.py

@@ -262,7 +262,7 @@ class MessageQueueUUIDStore(object):
             raise
 
     def keys(self):
-        return iter(os.listdir(self.__store))
+        return iter(listdir(self.__store))
 
     def get_time(self, key):
         try: