How to trap warnings? (no replies)

I'm using python 2.6 with the MySQLdb module.
Server version: 5.1.41-3ubuntu12.10 (Ubuntu)

In the past I have used _mysql_exceptions to raise exceptions for warnings.
Example

## instantiate cursor
self.__rdb = self.__conn.cursor()
## Execute a command 
try :
  self.__rdb.execute(command)
except _mysql_exceptions.Warning,e:
  ... ## exception handling here

But this approach does not appear to work any long
I'm just getting warnings of truncated data sent to stdout.
Please advise
TIA