"Heikki Linnakangas" <heikki(at)enterprisedb(dot)com> writes:
> Looking closer, I don't understand how that change was supposed to do
> anything.
The point of that patch is to avoid an off-by-one result for years BC.
The direction of rounding in integer division with a negative numerator
is undefined in C (or at least used to be --- did C99 tighten this up?).
regards, tom lane