Pulp

$ http POST http://127.0.0.1:8000/api/v3/repositories/ name=file_repo

HTTP/1.0 400 Bad Request
Allow: GET, POST, HEAD, OPTIONS
Content-Length: 78
Content-Type: application/json
Date: Sat, 29 Jul 2017 12:00:46 GMT
Server: WSGIServer/0.2 CPython/3.5.3
Vary: Accept, Cookie
X-Frame-Options: SAMEORIGIN

{
    "notes": [
        "This field is required."
    ],
    "scratchpad": [
        "This field is required."
    ]
}

It should be possible to create repo with just name provided.
Scratchpad field will be removed in #2817.