OS API v1.1 bad error on server create with invalid flavor

When I create a server at /v1.1/servers with an invalid flavorRef in the POST body, I get the following response:

---
status : 400
content-length : 147
content-type : text/plain; charset=UTF-8
400 Bad Request

The server could not comply with the request since it is either malformed or otherwise incorrect.

 could not parse id from href
---

The content type should not be text/plain--it should respect the accept header. Additionally, the message should be formatted correctly (as in the following json example)

{
    "badRequest": {
         "code": 400,
         "message": ...,
         "details": ...
    }
}