mkswap overwrites existing partitions

Setup was software raid 1 with 4 partitions, root, home, srv and swap. Swap would not mount and computer would not restart correctly, but then this was on feisty herd 5, and that's a seperate bug.

But the bug is that when trying to mount the swap, doing mkswap and swapon, I accidentally put the /srv partition as a param and mkswap converted a mounted ext3 partition into a swap space without asking any questions.

I don't know if this is only when dealing with software raid partitions or a problem in general, but this is clearly a bug. This operation should not be allowed on a mounted drive and not on a drive not marked for another filesystem.