Getting "ERROR: did not find all requested child rels inappend_rel_list" when enable_partition_pruning is on

I am getting "ERROR:  did not find all requested child rels in append_rel_list" when enable_partition_pruning is on for below test case.

CREATE TABLE test(c1 int, c2 int) PARTITION BY RANGE(c1);
CREATE TABLE test_p1 PARTITION OF test FOR VALUES FROM (minvalue) TO (0);
CREATE TABLE test_p2 PARTITION OF test FOR VALUES FROM  (0) TO (maxvalue);
select * from (select * from test a union all select *  from test b) ss where (c1 >= c2);

postgres=# set enable_partition_pruning to off;
SET
postgres=# select * from (select * from test a union all select *  from test b) ss where (c1 >= c2);
 c1 | c2
----+----
(0 rows)

postgres=#
postgres=# set enable_partition_pruning to on;
SET
postgres=# select * from (select * from test a union all select *  from test b) ss where (c1 >= c2);
ERROR:  did not find all requested child rels in append_rel_list