msg_id and session missing in "execution_state": "dead" status

The final state doesn't include session
id or msg_id (https://github.com/sagemath/sagecell/wiki/Session):

{
    "content": {
        "execution_state": "dead"
    },
    "header": {
        "msg_type": "status"
    },
    "parent_header": {},
    "metadata": {}
}

It would make the whole protocol more uniform
if really all messages had the session and msg_id fields.