Getting return values from a MySQL stored procedure in Python, using MySQLdb

Question

I've got a stored procedure in a MySQL database that simply updates a date column and returns the previous date. If I call this stored procedure from the MySQL client, it works fine, but when I try to call the stored procedure from Python using MySQLdb I can't seem to get it to give me the return value.

Here's the code to the stored procedure:

CREATE PROCEDURE test_stuff.get_lastpoll()
BEGIN
    DECLARE POLLTIME TIMESTAMP DEFAULT NULL;
    START TRANSACTION;

    SELECT poll_date_time
      FROM test_stuff.poll_table
      LIMIT 1 
      INTO POLLTIME
    FOR UPDATE;

    IF POLLTIME IS NULL THEN
        INSERT INTO 
               test_stuff.poll_table 
               (poll_date_time)
        VALUES 
               ( UTC_TIMESTAMP() );

        COMMIT;
        SELECT NULL as POLL_DATE_TIME;
    ELSE
        UPDATE test_stuff.poll_table SET poll_date_time = UTC_TIMESTAMP();
        COMMIT;
        SELECT DATE_FORMAT(POLLTIME, '%Y-%m-%d %H:%i:%s') as POLL_DATE_TIME;
    END IF;
END

The code I'm using to try to call the stored procedure is similar to this:

#!/usr/bin/python

import sys
import MySQLdb

try:
    mysql = MySQLdb.connect(user=User,passwd=Passwd,db="test_stuff")
    mysql_cursor = mysql.cursor()

    results=mysql_cursor.callproc( "get_lastpoll", () )
    print results

    mysql_cursor.close()
    mysql.close()

except MySQLdb.Error, e:
    print "MySQL Error %d:  %s" % ( e.args[0], e.args[1] )
    sys.exit(1)

I know that you can do IN and OUT parameters, but from what I can determine from the MySQLdb documentation, this isn't possible with MySQLdb. Does anyone have any clue how I could get the results of the stored procedure?

If I run it from a SQL tool, here's the output:

POLL_DATE_TIME       
-------------------  
2009-02-18 22:27:07  

If I run the Python script, it returns back an empty set, like this:

()