Another question. Is Peter's branch up to date with
jsonb_populate_record() ? From discussions on list it sounds like the
plan was to get rid of the use_json_as_text argument but his patch
still has it.
(Tangentially, I wonder if it wouldn't be possible to make this a
plain cast. I'm not sure but I think it's possible to have a cast to a
polymorphic type and peek at runtime at the record definition to
determine what to do).