Sort the backup times before deleting snapshots to be sure the time o…

…rder is correct between the timing of the first snapshot of the month and the timing of the snapshot from four weeks ago.

boto/ec2/connection.py

@@ -1392,7 +1392,8 @@ def trim_snapshots(self, hourly_backups = 8, daily_backups = 7, weekly_backups =
                 temp.append(t)
 
         target_backup_times = temp
-        target_backup_times.reverse() # make the oldest date first
+        target_backup_times.sort() # make the oldeest dates first, and make sure the month start and last four week's
+                                   # start are in the proper order
 
         # get all the snapshots, sort them by date and time, and organize them into one array for each volume:
         all_snapshots = self.get_all_snapshots(owner = 'self')