[Gordonjcp]

I had a thing recently where someone was updating some entries on a system I look after, decided the changes hadn't applied properly, and clicked "Roll back" to put it back to its original state.

Whatever had gotten into it, it rolled back to 2009. It rolled everything back, including user accounts.

No-one who worked there in 2009 still worked there, so no-one had a valid password any more.

Fortunately it was easy enough to copy the last-but-one backup over the top and lose the day before's config updates, and cure its Flowers for Algernon state, but it was a pretty hairy afternoon.