Py3/py2 issue in task output serialization

[Xarthisius]

[2018-07-03 02:16:29,079] ERROR: 500 Error
Traceback (most recent call last):
  File "/usr/local/lib/python3.5/dist-packages/kombu/serialization.py", line 50, in _reraise_errors
    yield
  File "/usr/local/lib/python3.5/dist-packages/kombu/serialization.py", line 263, in loads
    return decode(data)
  File "/usr/local/lib/python3.5/dist-packages/jsonpickle/__init__.py", line 155, in decode
    return unpickler.decode(string, backend=backend, keys=keys, classes=classes)
  File "/usr/local/lib/python3.5/dist-packages/jsonpickle/unpickler.py", line 26, in decode
    return context.restore(backend.decode(string), reset=reset, classes=classes)
  File "/usr/local/lib/python3.5/dist-packages/jsonpickle/backend.py", line 194, in decode
    return self.backend_decode(name, string)
  File "/usr/local/lib/python3.5/dist-packages/jsonpickle/backend.py", line 206, in backend_decode
    return self._decoders[name](string, *optargs, **decoder_kwargs)
  File "/usr/lib/python3.5/json/__init__.py", line 312, in loads
    s.__class__.__name__))
TypeError: the JSON object must be str, not 'bytes'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/girder/girder/api/rest.py", line 620, in endpointDecorator
    val = fun(self, args, kwargs)
  File "/girder/girder/api/rest.py", line 1208, in PUT
    return self.handleRoute('PUT', path, params)
  File "/girder/girder/api/rest.py", line 947, in handleRoute
    val = handler(**kwargs)
  File "/girder/girder/api/access.py", line 88, in wrapped
    return fun(*args, **kwargs)
  File "/girder/girder/api/rest.py", line 467, in wrapped
    val = fun(*args, **kwargs)
  File "/girder/girder/api/describe.py", line 702, in wrapped
    return fun(*args, **kwargs)
  File "/girder/plugins/jobs/server/job_rest.py", line 181, in updateJob
    progressMessage=progressMessage)
  File "/girder/plugins/jobs/server/models/job.py", line 408, in updateJob
    'job': job
  File "/girder/girder/events.py", line 310, in trigger
    handler['handler'](e)
  File "/girder/plugins/wholetale/server/models/instance.py", line 189, in finalizeInstance
    service = getCeleryApp().AsyncResult(job['celeryTaskId']).get()
  File "/usr/local/lib/python3.5/dist-packages/celery/result.py", line 224, in get
    on_message=on_message,
  File "/usr/local/lib/python3.5/dist-packages/celery/backends/async.py", line 188, in wait_for_pending
    for _ in self._wait_for_pending(result, **kwargs):
  File "/usr/local/lib/python3.5/dist-packages/celery/backends/async.py", line 250, in _wait_for_pending
    self.on_wait_for_pending(result, timeout=timeout, **kwargs)
  File "/usr/local/lib/python3.5/dist-packages/celery/backends/redis.py", line 110, in on_wait_for_pending
    for meta in result._iter_meta():
  File "/usr/local/lib/python3.5/dist-packages/celery/result.py", line 414, in _iter_meta
    return iter([self._get_task_meta()])
  File "/usr/local/lib/python3.5/dist-packages/celery/result.py", line 410, in _get_task_meta
    return self._maybe_set_cache(self.backend.get_task_meta(self.id))
  File "/usr/local/lib/python3.5/dist-packages/celery/backends/base.py", line 359, in get_task_meta
    meta = self._get_task_meta_for(task_id)
  File "/usr/local/lib/python3.5/dist-packages/celery/backends/base.py", line 674, in _get_task_meta_for
    return self.decode_result(meta)
  File "/usr/local/lib/python3.5/dist-packages/celery/backends/base.py", line 278, in decode_result
    return self.meta_from_decoded(self.decode(payload))
  File "/usr/local/lib/python3.5/dist-packages/celery/backends/base.py", line 285, in decode
    accept=self.accept)
  File "/usr/local/lib/python3.5/dist-packages/kombu/serialization.py", line 263, in loads
    return decode(data)
  File "/usr/lib/python3.5/contextlib.py", line 77, in __exit__
    self.gen.throw(type, value, traceback)
  File "/usr/local/lib/python3.5/dist-packages/kombu/serialization.py", line 54, in _reraise_errors
    reraise(wrapper, wrapper(exc), sys.exc_info()[2])
  File "/usr/local/lib/python3.5/dist-packages/vine/five.py", line 178, in reraise
    raise value.with_traceback(tb)
  File "/usr/local/lib/python3.5/dist-packages/kombu/serialization.py", line 50, in _reraise_errors
    yield
  File "/usr/local/lib/python3.5/dist-packages/kombu/serialization.py", line 263, in loads
    return decode(data)
  File "/usr/local/lib/python3.5/dist-packages/jsonpickle/__init__.py", line 155, in decode
    return unpickler.decode(string, backend=backend, keys=keys, classes=classes)
  File "/usr/local/lib/python3.5/dist-packages/jsonpickle/unpickler.py", line 26, in decode
    return context.restore(backend.decode(string), reset=reset, classes=classes)
  File "/usr/local/lib/python3.5/dist-packages/jsonpickle/backend.py", line 194, in decode
    return self.backend_decode(name, string)
  File "/usr/local/lib/python3.5/dist-packages/jsonpickle/backend.py", line 206, in backend_decode
    return self._decoders[name](string, *optargs, **decoder_kwargs)
  File "/usr/lib/python3.5/json/__init__.py", line 312, in loads
    s.__class__.__name__))
kombu.exceptions.DecodeError: the JSON object must be str, not 'bytes'
Additional info:
  Request URL: PUT https://girder.dev.wholetale.org/api/v1/job/5b3adc7814373f0001debcb6
  Query string: 
  Remote IP: 10.0.0.2

Workaround applied: whole-tale/girder@6871ca8