@Override
  public boolean isTxnAborted(long txnid) {
    int index = Arrays.binarySearch(exceptions, txnid);
    return index >= 0 && abortedBits.get(index);
  }
txnlist is represented in ranges like this: 10-20,14,16-50
if the range is smaller then 5 it will not get merged, to avoid unnecessary overhead
@param txnListString string to parse from
@return txn list
storage-api/src/java/org/apache/hadoop/hive/common/ValidReadTxnList.java