pre-rebase safety hook

Is anyone aware of a pre-rebase hook script that will prevent (or at
least warn) you from letting a rebase rewrite a commit that has been
pushed or merged into any branch except it's own?

I've activated the pre-rebase.sample, and it does seem to give me any
warnings at all:

Here's the terminal output demonstrating what I mean:

http://pastie.org/331082

Thanks!

Tim