Cannot move requirements to the backlog

[fracture91]

1. Create an iteration
2. Create a requirement with a title, description
3. Assign an estimate to the requirement, update
4. Assign the requirement to the iteration you created, update
5. Change the iteration drop-down back to backlog, update

The iteration dropdown just flips back to the iteration you created when you click update. There is no new history entry. I can change to different iterations without problems. Commit 5eeb75b

[fracture91]

I am able to move the requirement to the backlog by editing the requirement from the All Requirements tab.

[alexhenning]

It should go to the backlog if the estimate goes to 0. Editing in the multiple edit view is another bug.