Team Foundation Server - Unshelving

Why does TFS ask us if we want to save changes to our local project when we unshelve a shelveset for that same project? The fact that we are unshelving changes obviously means we want to overwrite any local changes with the shelveset files. So why would they ask us that question? If you click No to saving changes, you're probably fine. But if you click yes - BOOM! Errors abound. You have to undo the pending changes you just unshelved, then unshelve them again. What a waste of time. Better hope you preserved the shelveset or took a backup, because if you didn't you're fucked.