ExecEvalExpr: unknown expression type 501 from coalesce

With 7.0.2, there seems to be another coalesce weirdness:

pjw=# create table tb(i int);
CREATE
pjw=# create table tbx(o int, n int);
CREATE
pjw=# update tb set i = coalesce((select n from tbx x where x.o = tb.i),tb.i);
UPDATE 0
pjw=# insert into tb values(1);
INSERT 1379795 1
pjw=# insert into tb values(2);
INSERT 1379796 1
pjw=# insert into tb values(0);
INSERT 1379797 1
pjw=# insert into tbx values(1,2);
INSERT 1379798 1
pjw=# insert into tbx values(2,1);
INSERT 1379799 1
pjw=# update tb set i = coalesce((select n from tbx x where x.o = tb.i),tb.i);
ERROR:  ExecEvalExpr: unknown expression type 501


This seems to be fixed in current CVS but I'd be interested in a patch for
7.0.2, if there is one...


----------------------------------------------------------------
Philip Warner                    |     __---_____
Albatross Consulting Pty. Ltd.   |----/       -  \
(A.C.N. 008 659 498)             |          /(@)   ______---_
Tel: (+61) 0500 83 82 81         |                 _________  \
Fax: (+61) 0500 83 82 82         |                 ___________ |
Http://www.rhyme.com.au          |                /           \|
                                 |    --________--
PGP key available upon request,  |  /
and from pgp5.ai.mit.edu:11371   |/