Checking for empty change note on issue creation

I've been trying to add to the "new reaction" detector a check for a missing/empty change note. It seems like what I need is to import Reject and then Reject the creation with an error message, but it looks like Reject only works in an auditor, not a reactor.

It's a bit of a chicken-and-egg problem -- we currently accept the empty change note but without it, there's no message from which we can get the author id. I don't want to make change note required always -- just at the time of creation.

Any ideas (including pointers to documentation if appropriate)?

Thanks.

-- 
  David Hancock
  [email protected]