Re: ERROR: wrong varnullingrels (b 3) (expected (b)) for Var 2/1

Thanks for the report!  Reproduced here.  Also it can be reproduced with
subquery, as long as the subquery is not pulled up.

SELECT *
  FROM (VALUES (1)) t(c)
  LEFT JOIN t ljl1 ON true
  LEFT JOIN LATERAL (SELECT * FROM t WHERE t.n = ljl1.n offset 0) ljl2 ON ljl1.n = 1;
ERROR:  wrong varnullingrels (b 3) (expected (b)) for Var 2/1

When we transform the first form of identity 3 to the second form, we've
converted Pb*c to Pbc in deconstruct_distribute_oj_quals.  But we
neglect to consider that rel C might be a RTE_SUBQUERY and contains
quals that have lateral references to B.  So the B vars in such quals
have wrong nulling bitmaps and we'd finally notice that when we do
fix_upper_expr for the NestLoopParam expressions.

Thanks
Richard