Workflow registration fails on custom base classes

[pior]

(Pdb) workflows[0]
<class 'monaco.workflows.BaseWorkflow'>
(Pdb) workflows[0].name
(Pdb) c
INFO:caravan.commands.decider:Registering workflow types
Traceback (most recent call last):
  File "/home/pior/.virtualenvs/monaco/bin/caravan-decider", line 11, in <module>
    sys.exit(Command.main())
  File "/home/pior/.virtualenvs/monaco/local/lib/python2.7/site-packages/caravan/commands/base.py", line 28, in main
    response = cmd._run()
  File "/home/pior/.virtualenvs/monaco/local/lib/python2.7/site-packages/caravan/commands/base.py", line 105, in _run
    return self.run()
  File "/home/pior/.virtualenvs/monaco/local/lib/python2.7/site-packages/caravan/commands/decider.py", line 38, in run
    if self.args.register_workflows:
  File "/home/pior/.virtualenvs/monaco/local/lib/python2.7/site-packages/caravan/commands/decider.py", line 76, in register_workflow
    **args
  File "/home/pior/.virtualenvs/monaco/local/lib/python2.7/site-packages/botocore/client.py", line 310, in _api_call
    return self._make_api_call(operation_name, kwargs)
  File "/home/pior/.virtualenvs/monaco/local/lib/python2.7/site-packages/botocore/client.py", line 383, in _make_api_call
    api_params, operation_model, context=request_context)
  File "/home/pior/.virtualenvs/monaco/local/lib/python2.7/site-packages/botocore/client.py", line 425, in _convert_to_request_dict
    api_params, operation_model)
  File "/home/pior/.virtualenvs/monaco/local/lib/python2.7/site-packages/botocore/validate.py", line 273, in serialize_to_request
    raise ParamValidationError(report=report.generate_report())
botocore.exceptions.ParamValidationError: Parameter validation failed:
Invalid type for parameter version, value: None, type: <type 'NoneType'>, valid types: <type 'basestring'>
Invalid type for parameter name, value: None, type: <type 'NoneType'>, valid types: <type 'basestring'>