Berkeley DB Family

Hello.

I have a problem with python implementation in transaction and deadlock handling. The sequence is simple:
1. I'm making the transaction, and then run the reading query and handle deadlocks using DB_TXN_NOWAIT and lazy context evaluation. I'm doing this in one single try-except block. Something like that

try:
   context = manager.createQueryContext()
   context.setEvaluationType(context.Lazy)
   result = query.execute(txn, context)
except XmlException, exp:
   # some deadlock and other error handling here

2. In the other try-except block I'm trying to fetch the results using result.next like this:

try:
    res = result.next()
except StopIteration:
   # No result handling here

So, the problem is that in lazy context the database is queried again, but I cannot catch the XmlException, because only RuntimeError throws if i.e. deadlock happen here like this way:

try:
    res = result.next()
except StopIteration:
   # No result handling here
except XmlException, exp:
   # Deadlock could be here, but this block will never be run

RuntimeError has only string variable, even not having an error code, and I have to parse this string to detect if it is a deadlock error or any other.
I've found a small, but not good-enough(as I think) workaround here:

try:
    if result.hasNext():
       res = result.next()
   else:
       # No result handling here
except XmlException, exp:
     # Deadlock handling here

In this code I'm still not sure, the operation is atomic, and - as I understand - the possibility of catching RuntimeError instead of XmlException still exists. In addition, I have 2 reading operations instead of 1, so more deadlocks will happen.

Thanks in advance.

UPDATE: Forgot to say, that I'm using the latest release 2.4.16.1