Comment 1 for bug 925496

This behavior is by design.

The HTTP spec makes no assertions that a successful PUT operation MUST return a response body, and our specification takes advantage of that (see quotations below).

From our OS-KSADM API specification:

    2.1.1.6. Add Global roles to a user:
    "This operation does not require a request body and does not return a response body."

    2.1.2.7. Add roles to a user on a tenant:
    "This operation does not require a request body and does not return a response body."

In this specific case, the presence of a response body would be more likely attributed with a failure condition (error message).

Clients should NOT expect a response body; additionally, this behavior has recently changed in python-keystoneclient (see https://github.com/openstack/python-keystoneclient/commit/2914c2b1d1e36aa12ba5bd9b4c2ee9b594f1a79c ).