use new request for each statperiod (avoid cnx.close bug) closes #2218511

ccplugin.py

@@ -121,7 +121,7 @@ class StatsUpdater(object):
         elif periodicity == 'hour':
             start = datetime(chosendate.year, chosendate.month, chosendate.day, chosendate.hour)
             stop = datetime(chosendate.year, chosendate.month, chosendate.day, chosendate.hour, 59, 59)
-        return get_or_create_statperiod(self.session, start, stop, stats_report)
+        return get_or_create_statperiod(self.cnx.request(), start, stop, stats_report)
 
     ## update API #############################################################
     def update_stats(self, skip_compress=False):