Union Operations returns collections containing empty elements

[nbvfgh]

DROP TABLE t1;
DROP TABLE t2;
CREATE TABLE t1(geom geometry);
CREATE TABLE t2(geom geometry);

INSERT INTO t1 VALUES('GEOMETRYCOLLECTION(POLYGON EMPTY, POINT EMPTY, LINESTRING(10 10, 10 10))'::geometry);
INSERT INTO t2 VALUES('POINT(1 1)'::geometry);

-- Union
SELECT ST_AsText(ST_Union(t1.geom, t2.geom)) FROM t1, t2;
-- result{GEOMETRYCOLLECTION(POLYGON EMPTY,POINT EMPTY,LINESTRING(0 0,0 0),POINT(1 1))}

-- Unary Union
SELECT ST_AsText(ST_UnaryUnion(ST_Collect(ARRAY[t1.geom, t2.geom]))) FROM t1, t2;
-- result:{GEOMETRYCOLLECTION(POINT(1 1),LINESTRING EMPTY)}

bug is that "the overlay operations should not return collections containing empty elements".

[nbvfgh]

bug tracker: libgeos/geos#1224