If there are aggregation queries with aliases same as the table actual
columns and they are propagated further from subqueries and grouping is
applied on the column alias it may result in inconsistent targetlists
for aggregation plan causing crash.

	CREATE TABLE t1 (a int) DISTRIBUTED RANDOMLY;
	SELECT substr(a, 2) as a
	FROM
		(SELECT ('-'||a)::varchar as a
			FROM (SELECT a FROM t1) t2
		) t3
	GROUP BY a;