~TempRecoveryUnitSwap() {
     boost::scoped_ptr<RecoveryUnit> deleting(_txn->releaseRecoveryUnit());
     _txn->setRecoveryUnit(_oldRecoveryUnit);
 }
 TempRecoveryUnitSwap(OperationContext *txn)
     : _txn(txn),
       _oldRecoveryUnit(checked_cast<KVRecoveryUnit *>(_txn->releaseRecoveryUnit())) {
     _txn->setRecoveryUnit(_oldRecoveryUnit->newRecoveryUnit());
 }