impl_zmq should not triple-include context on call()

[Erica Windisch]

impl_zmq is including three copies of the context in the '-reply' cast during call().

Because we need compatibility with Grizzly (N-1 support), this should be reduced to two copies for Havana, before stripping down to a singular copy for I.

For instance:

            _cast(addr, context, topic, payload, envelope)

where envelope contains the following message:

    {
        'method': '-reply',
        'args': {
            'msg_id': msg_id,
            'topic': reply_topic,
            context: context
            'msg': [RpcContext.marshal(context), msg]
        }
    }

Two copies exist in the message itself, plus one sent to _cast (which injects the context into the ZMQ envelope)

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/24742

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/24742
Committed: http://github.com/openstack/oslo-incubator/commit/85e9e0622c96a3d2e0237e7a7bf089a1343ef545
Submitter: Jenkins
Branch: master

commit 85e9e0622c96a3d2e0237e7a7bf089a1343ef545
Author: Eric Windisch <email address hidden>
Date: Mon Mar 18 22:07:02 2013 -0400

    Eliminate multiple contexts in zmq call()

    Because we need compatibility with Grizzly (N-1 support), this should be
    reduced to two copies for Havana, before stripping down to a singular
    copy for I.

    The '-reply' request has its context key removed, with the
    msg option maintaining one extra copy of context until I.
    A TODO has been entered to clean this up following the Havana release.

    This fix eliminates an extra JSON double-deserialization routine.
    The double-serialization of context is still performed for Grizzly
    compatibility.

    fixes bug 1156956

    Change-Id: I071e382ec9c7e0df3794fe9ca574a5722f8910a6