Use default timeout setting as parent when using continueAsNew

Author: kefuzhao

swf/models/decision/workflow.py

@@ -55,8 +55,8 @@ def terminate(self, reason=None, details=None):
  })
 
  @decision_action
- def continue_as_new(self, child_policy=CHILD_POLICIES.TERMINATE,
- execution_timeout='300', task_timeout='300',
+ def continue_as_new(self, child_policy=None,
+ execution_timeout=None, task_timeout=None,
  input=None, tag_list=None, task_list=None,
  workflow_type_version=None):
  """Coninue as new workflow execution decision builder