Fix deepcopy() error with copying the errback method from PulsarExchange.

[natefoo]

Otherwise, if retry options are enabled, you get this:

galaxy.jobs.runners.pulsar ERROR 2015-09-11 09:59:04,994 failure running job 433893
Traceback (most recent call last):
  File "/galaxy-repl/instances/test/server/lib/galaxy/jobs/runners/pulsar.py", line 224, in queue_job
    job_id = pulsar_submit_job(client, client_job_description, remote_job_config)
  File "/galaxy-repl/instances/test/server/lib/pulsar/client/staging/up.py", line 43, in submit_job
    client.launch(**launch_kwds)
  File "/galaxy-repl/instances/test/server/lib/pulsar/client/client.py", line 314, in launch
    response = self.client_manager.exchange.publish("setup", launch_params)
  File "/galaxy-repl/instances/test/server/lib/pulsar/client/amqp_exchange.py", line 198, in publish
    publish_kwds = self.__prepare_publish_kwds(publish_log_prefix)
  File "/galaxy-repl/instances/test/server/lib/pulsar/client/amqp_exchange.py", line 230, in __prepare_publish_kwds
    publish_kwds = copy.deepcopy(self.__publish_kwds)
  File "/srv/galaxy/test/python/lib/python2.7/copy.py", line 163, in deepcopy
    y = copier(x, memo)
  File "/srv/galaxy/test/python/lib/python2.7/copy.py", line 257, in _deepcopy_dict
    y[deepcopy(key, memo)] = deepcopy(value, memo)
  File "/srv/galaxy/test/python/lib/python2.7/copy.py", line 163, in deepcopy
    y = copier(x, memo)
  File "/srv/galaxy/test/python/lib/python2.7/copy.py", line 257, in _deepcopy_dict
    y[deepcopy(key, memo)] = deepcopy(value, memo)
  File "/srv/galaxy/test/python/lib/python2.7/copy.py", line 163, in deepcopy
    y = copier(x, memo)
  File "/srv/galaxy/test/python/lib/python2.7/copy.py", line 264, in _deepcopy_method
    return type(x)(x.im_func, deepcopy(x.im_self, memo), x.im_class)
  File "/srv/galaxy/test/python/lib/python2.7/copy.py", line 190, in deepcopy
    y = _reconstruct(x, rv, 1, memo)
  File "/srv/galaxy/test/python/lib/python2.7/copy.py", line 334, in _reconstruct
    state = deepcopy(state, memo)
  File "/srv/galaxy/test/python/lib/python2.7/copy.py", line 163, in deepcopy
    y = copier(x, memo)
  File "/srv/galaxy/test/python/lib/python2.7/copy.py", line 257, in _deepcopy_dict
    y[deepcopy(key, memo)] = deepcopy(value, memo)
  File "/srv/galaxy/test/python/lib/python2.7/copy.py", line 190, in deepcopy
    y = _reconstruct(x, rv, 1, memo)
  File "/srv/galaxy/test/python/lib/python2.7/copy.py", line 329, in _reconstruct
    y = callable(*args)
  File "/srv/galaxy/test/venv/lib/python2.7/copy_reg.py", line 93, in __newobj__
    return cls.__new__(cls, *args)
TypeError: object.__new__(thread.lock) is not safe, use thread.lock.__new__()