#427 Some statment stucks with EXECUTE DIRECT

[Koichi Suzuki]

The following satement stucks. It used to work at 1.0.x.
Running this with direct connection to a datanode works correctly.

EXECUTE DIRECT ON (someDataNode) $$
SELECT
count(*)
FROM
(SELECT * FROM pg_locks l LEFT JOIN
(SELECT * FROM pg_stat_activity) s ON l.database = s.datid) a
$$

[Koichi Suzuki]

Test this with 1.2.