contract OrderValidator is Executor, ZoneInteraction {
    function _validateBasicOrderAndUpdateStatus( ... ) ... {
        ...
        _verifyOrderStatus(
            orderHash,
            orderStatus,
            true, // Only allow unused orders when fulfilling basic orders.
            true // Signifies to revert if the order is invalid.
        );
     ...
    _orderStatus[orderHash].numerator = 1;
    ...
    }
}
contract Verifiers is Assertions, SignatureVerification {
    function _verifyOrderStatus(..., bool onlyAllowUnused, ... ) ... {
        ...      
        if (orderStatus.numerator != 0) {  // the second time numerator == 1
            if (onlyAllowUnused) {   // true
                revert OrderPartiallyFilled(orderHash);  // misleading message
                ...
            }
        }
    }
} 
 revert OrderPartiallyFilled(orderHash);
