Bug in PostrgeSQL 8.0beta

Hello,

I downloaded and install postgresql-8.0.0beta3.tar.gz

I create the following table:
CREATE OR REPLACE FUNCTION "ayz"."my_lower" (text) RETURNS text AS'
BEGIN
return lower($1);
END;
'LANGUAGE 'plpgsql' IMMUTABLE RETURNS NULL ON NULL INPUT SECURITY INVOKER;

CREATE TABLE public.art
(
art_id int4 NOT NULL,
art_name "varchar"(60),
art_costin "numeric"(15,2),
art_costout "numeric"(15,2),
rem "varchar"(60),
art_country_name "varchar"(25),
art_firm_name "varchar"(35),
art_price_name "varchar"(100) DEFAULT 'wwww'::character varying,
CONSTRAINT art_pkey PRIMARY KEY (art_id)
)
WITH OIDS;

CREATE INDEX art_art_name_idx
ON public.art
USING btree
(my_lower(art_name::text));
ALTER TABLE public.art CLUSTER ON art_art_name_idx;

Executing the following query return an error 'ERROR: unrecognized node type: 656'.
SELECT pg_get_expr(i.indexprs, i.indrelid) AS expr
FROM pg_index i
INNER JOIN pg_class c ON i.indrelid = c.oid
WHERE c.relname = 'art'

Expression tree is
({FUNCEXPR :funcid 4061872 :funcresulttype 25 :funcretset false :funcformat 0 :args ({RELABELTYPE :arg {VAR :varno 1 :varattno 2 :vartype 1043 :vartypmod 64 :varlevelsup 0 :varnoold 1 :varoattno 2} :resulttype 25 :resulttypmod -1 :relabelformat 1})})

Thanks,

Alexander