LP:623300 - Query with join_cache_level = 6 returns extra rows in maria-5.3-dsmrr-cpk

The following query:

SELECT table2 .`col_int_nokey`, table1 .`col_int_nokey` FROM CC table1 JOIN C table2 ON table2 .`pk` = table1 .`col_int_nokey` WHERE table1 .`pk` ;

returns one row where table1 .`col_int_nokey` is NULL even though the ON condition should not match such rows.

maria-5.3 is not affected.