In commit 462bd95705, I changed postgres_fdw
to rely on get_plan_rowmark() instead of get_parse_rowmark(). I still
think that's a good idea in the long run, but as Etsuro Fujita pointed out,
it doesn't work today because planner.c forces PlanRowMarks to have
markType = ROW_MARK_COPY for all foreign tables. There's no urgent reason
to change this in the back branches, so let's just revert that part of
yesterday's commit rather than trying to design a better solution under
time pressure.
Also, add a regression test case showing what postgres_fdw does with FOR
UPDATE/SHARE. I'd blithely assumed there was one already, else I'd have
realized yesterday that this code didn't work.
8ec8760fc8