MERGE lacks ruleutils.c decompiling support!?

I made this function:

CREATE OR REPLACE FUNCTION test_fun()
RETURNS void
LANGUAGE SQL
BEGIN ATOMIC
MERGE INTO target
USING source s on s.id = target.id
WHEN MATCHED THEN
  UPDATE SET data = s.data
WHEN NOT MATCHED THEN
  INSERT VALUES (s.id, s.data);
end;

It appears to work fine, but:

regression=# \sf+ test_fun()
ERROR:  unrecognized query command type: 5

and it also breaks pg_dump.  Somebody screwed up pretty badly
here.  Is there any hope of fixing it for Monday's releases?

(I'd guess that decompiling the WHEN clause would take a nontrivial
amount of new code, so maybe fixing it on such short notice is
impractical.  But ugh.)

            regards, tom lane