Change fixture default host to localhost (#1305)

Author: asdaraujo

test/fixtures.py

@@ -191,22 +191,8 @@ def instance(cls, broker_id, zk_host, zk_port, zk_chroot=None,
             (host, port) = (parse.hostname, parse.port)
             fixture = ExternalService(host, port)
         else:
-            # force IPv6 here because of a confusing point:
-            #
-            #  - if the string "localhost" is passed, Kafka will *only* bind to the IPv4 address of localhost
-            #    (127.0.0.1); however, kafka-python will attempt to connect on ::1 and fail
-            #
-            #  - if the address literal 127.0.0.1 is passed, the metadata request during bootstrap will return
-            #    the name "localhost" and we'll go back to the first case. This is odd!
-            #
-            # Ideally, Kafka would bind to all loopback addresses when we tell it to listen on "localhost" the
-            # way it makes an IPv6 socket bound to both 0.0.0.0/0 and ::/0 when we tell it to bind to "" (that is
-            # to say, when we make a listener of PLAINTEXT://:port.
-            #
-            # Note that even though we specify the bind host in bracket notation, Kafka responds to the bootstrap
-            # metadata request without square brackets later.
             if host is None:
-                host = "[::1]"
+                host = "localhost"
             fixture = KafkaFixture(host, port, broker_id,
                                    zk_host, zk_port, zk_chroot,
                                    transport=transport,