output, ie, no OR immediately below an OR.  Otherwise we get Asserts or
wrong answers for cases such as
	select * from tenk1 a, tenk1 b
	where (a.ten = b.ten and (a.unique1 = 100 or a.unique1 = 101))
	   or (a.hundred = b.hundred and a.unique1 = 42);
Per report from Rafael Martinez Guerrero.