[boost] [optional] swapping initialized with uninitialized

Hi, When two optionals (one initialized and other not) are swaped, then the one value in uninitialized optional is constructed and the other one in initialized optional is destructed. IMHO it's not necessary. It should be more effective to swap optional's m_storages without any values constructiona and destruction. Is there any reason for the current implementation? Regards, Vaclav