I wrote:
> I wonder whether it is worth creating a C trigger function
> (probably in regress.c) specifically to exercise this situation.
Actually, that doesn't seem too bad at all. I propose applying
and back-patching the attached.
BTW, I noticed while doing this that the adjacent "funny_dup17"
trigger is dead code, and has been since commit 1547ee01 of
1999-09-29. I'm inclined to rip it out, because anyone looking
at regress.c would naturally assume that anything in there is
being exercised.
regards, tom lane