table can be NULL even if that column as a NOT NULL constraint.
Fix for ticket [6f2222d550f5b0ee7ed].
FossilOrigin-Name: 6f6fcbe4736b9468a495c684d5eebc8bfe5c566a
really restrict the left table but instead rows that fail to meet the condition
to be joined with NULL rows from the right table. (CVS 2725)
FossilOrigin-Name: ea10f9785e3c5248dafcc297f3a2c5465b6e0dba