title: Avoid OpenERP audittrail bug
body: <p>I'd like to manage OpenERP user's activity by installing the audittrail module.<br>
  After creating some rules ( define which user, which object and which activity (create, update..) will be monitored).  I update a product to see it works.<br>
  When I've tried to update a product i got the system error. Seeing the log, I get<br>
  <em>[2010-08-31 12:53:35,042]  Cursor not closed explicitly<br>
  [2010-08-31 12:53:35,043]  Cursor was created at /home/pilgrim/working/sources/addons/audittrail/audittrail.py:204</em><br>
  Here the line that causes error<br>
            cr = pooler.get_db(db).cursor()<br>
  Looking at sql_db.py, I get the comment  </p>
  
  <pre><code>def __del__(self):
      if not self.__closed:
          # Oops. 'self' has not been closed explicitly.
          # The cursor will be deleted by the garbage collector,
          # but the database connection is not put back into the connection
          # pool, preventing some operation on the database like dropping it.
          # This can also lead to a server overload.
          msg = "Cursor not closed explicitly\n"  \
                "Cursor was created at %s:%s" % self.__caller
          log(msg, netsvc.LOG_WARNING)
          self.close()
  </code></pre>
  
  <p>Since I'm new to Python, I don't know how to overcome this issue?<br>
  Any hint to get over this?<br>
  Thank</p>