Re: [GENERAL] 3rd time is a charm.....right sibling is not next child crash.

I wrote:
> it did occur to me that there is a simple way to ameliorate this
> problem: we could rearrange the code in _bt_pagedel() so it checks for
> this case before entering its critical section. Then, corruption of
> this kind is at least only an ERROR not a PANIC.

In particular, I propose the attached patch, which gets rid of
unnecessary PANIC cases in _bt_split as well as _bt_pagedel;
all of these get reported from the field every now and then.
In passing this also makes the error messages out of _bt_split
a bit more detailed.

FWIW, I think the original rationale for PANIC here was so we could
capture a core dump for study; but since no one has ever yet cooperated
by providing such a dump, it seems like not panicking is a better plan.

Barring objections, I plan to back-patch this as far as it will
conveniently go (looks like 8.2 or 8.3 or so).

regards, tom lane