Relax ORDER BY Ambiguity check for SET-Operators

select q1.* from default q1 UNION ALL select q2.* from default  q2 ORDER BY a;

{

    "requestID": "959878f2-c038-4b9a-9e60-8c5361ab1001",

    "errors": [

        {

            "code": 3000,

            "msg": "Ambiguous reference to field a."

        }

    ],

    "status": "fatal",

    "metrics": {

        "elapsedTime": "706.904µs",

        "executionTime": "683.289µs",

        "resultCount": 0,

        "resultSize": 0,

        "errorCount": 1

    }

}