Starting a new sprint does not close the previous sprint

On the first day of this new iteration, I created a new sprint, populated it with items from the backlog, and started the new sprint. Unfortunately, I did not close the previous sprint, which had a number of issues with open subtasks. I realize that I was supposed to close the previous sprint before opening the new sprint, but GreenHopper does not make it easy to recover from this mistake. In trying to maintain the sprint history for each issue, I had to manually edit the sprint number for each of the stories, removing the previous sprint from the Sprint Number list. For some lesser issues, I just did a bulk update.

I'm not sure there's much value in supporting multiple open sprints for a given RapidBoard, but if so, make it harder to mess up the iteration rituals.