Weird misinterpretation of EXECUTE in PL/pgSQL

PostgreSQL 8.2.1

This is OK:

test=# create function test1() returns int language plpgsql as $$begin execute 'select a, b'; end$$;
CREATE FUNCTION
test=# select test1();
ERROR: column "a" does not exist
LINE 1: select a, b
^
QUERY: select a, b
CONTEXT: PL/pgSQL function "test1" line 1 at execute statement

This is weird:

test=# create function test2() returns int language plpgsql as $$begin execute 'select a', 'b'; end$$;
/* Several arguments separated by comma -- doesn't make sense */
CREATE FUNCTION
test=# select test2();
ERROR: query "SELECT 'select a', 'b'" returned 2 columns
CONTEXT: PL/pgSQL function "test2" line 1 at execute statement

In the presence of a comma-separated list of arguments it seems to
intepret the EXECUTE command wildly differently. What is going on here?

--
Peter Eisentraut
http://developer.postgresql.org/~petere/