Well, I think it is (2). I added a few extra lines before the changed code and put a 'caught' message in the except clause that is now supposed to be catching IOError. And it is.  But the same traceback still shows up (except for the slightly different line number from this file). Beat's me what is going on.

32923eefca3c425f32] Caught Socket closed from (pid=2700) reconnect /usr/lib/python2.7/dist-packages/nova/rpc/impl_kombu.py:452
2012-03-30 15:32:46 ERROR nova.rpc.common [req-69a7c6c3-8d7e-4077-8ab5-fa3d8fbdd538 123634b20bc14ddf99e98bec730065e7 d1e6bada36404f\
32923eefca3c425f32] AMQP server on 172.18.0.146:5672 is unreachable: Socket closed. Trying again in 1 seconds.
(nova.rpc.common): TRACE: Traceback (most recent call last):
(nova.rpc.common): TRACE:   File "/usr/lib/python2.7/dist-packages/nova/rpc/impl_kombu.py", line 449, in reconnect
(nova.rpc.common): TRACE:     self._connect()
(nova.rpc.common): TRACE:   File "/usr/lib/python2.7/dist-packages/nova/rpc/impl_kombu.py", line 423, in _connect
(nova.rpc.common): TRACE:     self.connection.connect()
(nova.rpc.common): TRACE:   File "/usr/lib/python2.7/dist-packages/kombu/connection.py", line 154, in connect
(nova.rpc.common): TRACE:     return self.connection
(nova.rpc.common): TRACE:   File "/usr/lib/python2.7/dist-packages/kombu/connection.py", line 560, in connection
(nova.rpc.common): TRACE:     self._connection = self._establish_connection()
(nova.rpc.common): TRACE:   File "/usr/lib/python2.7/dist-packages/kombu/connection.py", line 521, in _establish_connection
(nova.rpc.common): TRACE:     conn = self.transport.establish_connection()
(nova.rpc.common): TRACE:   File "/usr/lib/python2.7/dist-packages/kombu/transport/pyamqplib.py", line 255, in establish_connection
(nova.rpc.common): TRACE:     connect_timeout=conninfo.connect_timeout)
(nova.rpc.common): TRACE:   File "/usr/lib/python2.7/dist-packages/kombu/transport/pyamqplib.py", line 52, in __init__
(nova.rpc.common): TRACE:     super(Connection, self).__init__(*args, **kwargs)
(nova.rpc.common): TRACE:   File "/usr/lib/python2.7/dist-packages/amqplib/client_0_8/connection.py", line 135, in __init__
(nova.rpc.common): TRACE:     (10, 10), # start
(nova.rpc.common): TRACE:   File "/usr/lib/python2.7/dist-packages/amqplib/client_0_8/abstract_channel.py", line 95, in wait
(nova.rpc.common): TRACE:     self.channel_id, allowed_methods)
(nova.rpc.common): TRACE:   File "/usr/lib/python2.7/dist-packages/amqplib/client_0_8/connection.py", line 202, in _wait_method
(nova.rpc.common): TRACE:     self.method_reader.read_method()
(nova.rpc.common): TRACE:   File "/usr/lib/python2.7/dist-packages/amqplib/client_0_8/method_framing.py", line 221, in read_method
(nova.rpc.common): TRACE:     raise m
(nova.rpc.common): TRACE: IOError: Socket closed
(nova.rpc.common): TRACE:
2012-03-30 15:32:46 DEBUG nova.rpc.common [req-842419d5-6fe6-4e99-b830-ec6112265362 123634b20bc14ddf99e98bec730065e7 d1e6bada36404f\
32923eefca3c425f32] Caught Socket closed from (pid=2700) reconnect /usr/lib/python2.7/dist-packages/nova/rpc/impl_kombu.py:452
2012-03-30 15:32:46 ERROR nova.rpc.common [req-842419d5-6fe6-4e99-b830-ec6112265362 123634b20bc14ddf99e98bec730065e7 d1e6bada36404f\
32923eefca3c425f32] AMQP server on 172.18.0.146:5672 is unreachable: Socket closed. Trying again in 1 seconds.
(nova.rpc.common): TRACE: Traceback (most recent call last):
(nova.rpc.common): TRACE:   File "/usr/lib/python2.7/dist-packages/nova/rpc/impl_kombu.py", line 449, in reconnect
(nova.rpc.common): TRACE:     self._connect()
(nova.rpc.common): TRACE:   File "/usr/lib/python2.7/dist-packages/nova/rpc/impl_kombu.py", line 423, in _connect
(nova.rpc.common): TRACE:     self.connection.connect()
(nova.rpc.common): TRACE:   File "/usr/lib/python2.7/dist-packages/kombu/connection.py", line 154, in connect
(nova.rpc.common): TRACE:     return self.connection
(nova.rpc.common): TRACE:   File "/usr/lib/python2.7/dist-packages/kombu/connection.py", line 560, in connection
(nova.rpc.common): TRACE:     self._connection = self._establish_connection()
(nova.rpc.common): TRACE:   File "/usr/lib/python2.7/dist-packages/kombu/connection.py", line 521, in _establish_connection
(nova.rpc.common): TRACE:     conn = self.transport.establish_connection()
(nova.rpc.common): TRACE:   File "/usr/lib/python2.7/dist-packages/kombu/transport/pyamqplib.py", line 255, in establish_connection
(nova.rpc.common): TRACE:     connect_timeout=conninfo.connect_timeout)
(nova.rpc.common): TRACE:   File "/usr/lib/python2.7/dist-packages/kombu/transport/pyamqplib.py", line 52, in __init__
(nova.rpc.common): TRACE:     super(Connection, self).__init__(*args, **kwargs)
(nova.rpc.common): TRACE:   File "/usr/lib/python2.7/dist-packages/amqplib/client_0_8/connection.py", line 135, in __init__
(nova.rpc.common): TRACE:     (10, 10), # start
(nova.rpc.common): TRACE:   File "/usr/lib/python2.7/dist-packages/amqplib/client_0_8/abstract_channel.py", line 95, in wait
(nova.rpc.common): TRACE:     self.channel_id, allowed_methods)
(nova.rpc.common): TRACE:   File "/usr/lib/python2.7/dist-packages/amqplib/client_0_8/connection.py", line 202, in _wait_method
(nova.rpc.common): TRACE:     self.method_reader.read_method()
(nova.rpc.common): TRACE:   File "/usr/lib/python2.7/dist-packages/amqplib/client_0_8/method_framing.py", line 221, in read_method
(nova.rpc.common): TRACE:     raise m
(nova.rpc.common): TRACE: IOError: Socket closed
(nova.rpc.common): TRACE:
201