TxnHandler.getOpenTxnsInfo() and getOpenTxns() may produce inconsistent result

both run at READ_COMMITTED isolation level and each runs 2 queries.
Thus it's possible for a new txn to start/commit after hight water mark is recored by these methods. So the returned list may have txns above the HWM.

This can be fixed by adding "WHERE TXN_ID < hwm" clause to 2nd query in each case