PL/Python: No stack trace for an exception

I am using plpythonu on postgres 9.0.2. One of my python functions was
throwing a TypeError exception. However, I only see the exception in the
database and not the stack trace. It becomes difficult to debug if the
stack trace is absent in Python.

logdb=# select get_words(forminput) from fi;
ERROR: PL/Python: TypeError: an integer is required
CONTEXT: PL/Python function "get_words"

And here is the error if I run that function on the same data in python:

Traceback (most recent call last):
File "valid.py", line 215, in <module>
parse_query(result['forminput'])
File "valid.py", line 132, in parse_query
dateobj = datestr_to_obj(columnHash[column])
File "valid.py", line 37, in datestr_to_obj
dateobj = datetime.date(words[2], words[1], words[0])
TypeError: an integer is required

Is this a known problem or this needs addressing?

Thanks,
Sushant.