Add regression test for bug fixed by recent refactoring.

Test case by Andres Freund for bug fixed by Tom Lane's refactoring
in commit 5194024d

src/test/regress/expected/matview.out

@@ -418,3 +418,15 @@ NOTICE:  drop cascades to 3 other objects
 DETAIL:  drop cascades to view v_test2
 drop cascades to materialized view mv_test2
 drop cascades to materialized view mv_test3
+-- test a corner case for "with no data" versus a query which yields no rows
+CREATE MATERIALIZED VIEW matview_unit_false AS SELECT false WHERE false WITH NO DATA;
+SELECT * FROM matview_unit_false;
+ERROR:  materialized view "matview_unit_false" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW matview_unit_false;
+SELECT * FROM matview_unit_false;
+ bool 
+------
+(0 rows)
+
+DROP MATERIALIZED VIEW matview_unit_false;

src/test/regress/sql/matview.sql

@@ -129,3 +129,10 @@ CREATE MATERIALIZED VIEW mv_test3 AS SELECT * FROM mv_test2 WHERE moo = 12345;
 SELECT pg_relation_is_scannable('mv_test3'::regclass);
 
 DROP VIEW v_test1 CASCADE;
+
+-- test a corner case for "with no data" versus a query which yields no rows
+CREATE MATERIALIZED VIEW matview_unit_false AS SELECT false WHERE false WITH NO DATA;
+SELECT * FROM matview_unit_false;
+REFRESH MATERIALIZED VIEW matview_unit_false;
+SELECT * FROM matview_unit_false;
+DROP MATERIALIZED VIEW matview_unit_false;