Unexpected results when the join condition contains the OR predicate

[suyZhong]

Considering the test case below.

CREATE TABLE t1(c0 BOOLEAN);
CREATE TABLE t0(c0 BOOLEAN, c1 BOOLEAN);
CREATE UNIQUE INDEX i0 ON t0(c1 , c0 );
INSERT INTO t0 (c0) VALUES (false);
INSERT INTO t1 (c0) VALUES (false);

SELECT * FROM t1, t0; -- false, false, null
SELECT NOT (false AND ((t1.c0 <= false) NOT IN (t0.c1))) FROM t1, t0; -- true
SELECT * FROM t1, t0 WHERE (NOT (false AND ((t1.c0 <= false) NOT IN (t0.c1))));
-- Expected: false, false, null
-- Actual: empty

The third SELECT returns an empty result, which is surprising: If the result of second query is true, the value of the NOT expression should be true, and thus the third query should return the row of the table after JOIN, that is false, false, null, same as the first query.

I found this in version LI-T6.0.0.170 where I built from source code 3dc03dd. Things work fine in v4.

[dyemanov]

Simplified condition that actually causes the trouble:
SELECT * FROM t1, t0 WHERE true OR (t1.c0 <= false) = t0.c1;