This was a known bug in an early version of the 2.0 beta, but is marked as resolved with code committed 6 days ago. How recently have you updated your local code?
The workaround in the meantime, if you need the raw JSON definition of api_docs or of any particular service, is to call the API at /api/v2/api_docs if you need the raw JSON for all services, or /api/v2/api_docs/{servicename} for the raw definition of a single service.