`process_orchestration` reading response with status code 400 raises exception in `response.read_json()`

Carlos Bocanera Gallardo found that when calling `add_orchestration_rule()`, if the response status code is 400 and the `process_orchestration` function raises an `OrchestrationError`, the `orchestration_response.read_json()` method raises a `RuntimeError`, which makes debugging hard.
The reason for raising the `RuntimeError` is that the `orchestration_response` is not a `"JSON"` response, or at least not a `constants.Payload.JSON` response. I am not sure why this is happening at the moment.