{
    "description": "Unexpected mongos", 
    "phases": [
        {
            "outcome": {
                "servers": {}, 
                "setName": "rs", 
                "topologyType": "ReplicaSetNoPrimary"
            }, 
            "responses": [
                [
                    "b:27017", 
                    {
                        "ismaster": true, 
                        "msg": "isdbgrid", 
                        "ok": 1
                    }
                ]
            ]
        }
    ], 
    "uri": "mongodb://b/?replicaSet=rs"
}