"Are you sure?" notice before importing settings

[j-falk]

We had a project now where we used the import / export functionality. Unfortunately we triggered an import on the wrong site which then obviously made us loose the existing configuration we had on that site.

Now even if this was definitely our own fault, and we did have full database backup that we restored, I think it would would have been nice with a notice when you import a file that asks you if you are sure you want to do the import, remind them of that the existing configuration will be lost and that you suggest that the user does an export before they do the import if they want to revert back.