Maybe—and the UI could be little more than a script that does exactly what you described.

The point of making it a UI is, first and foremost, to get people thinking about this question. And it gives people the option to acheive what you just described without stumbling upon a post like yours on Hacker News.

A post like mine? But it's your post that has the idea...? The only thing I said about how to make it possible is "separate backup", which anyone can think of in two seconds and is only a hint of a tenth of an explanation. I don't understand.