Excerpts from Tom Lane's message of vie jul 02 22:02:59 -0400 2010:
> Possibly. I was planning to go back and study that code a bit more ---
> I have a feeling that there might be some kind of rare concurrency bug
> involved in btree page deletion. But I've been up to my rear in
> other alligators for the past several weeks.
Judging from the evidence I've seen, I'm fairly sure that there *is* a
concurrency bug somewhere in that code.