Consider this query
SELECT t1.* FROM t1, (SELECT t2.b FROM t2 WHERE NOT EXISTS
(SELECT 1 FROM t3) GROUP BY b) sq where sq.b = t1.a;

If SELECT 1 FROM t3 is expensive, for example t3 has >
thd->variables.expensive_subquery_limit, first evaluation is deferred to
mysql_derived_fill().  There it is noted that, in the above case
 NOT EXISTS (SELECT 1 FROM t3) is constant and false.

This causes the join variable zero_result_cause to be set to
"Impossible WHERE noticed after reading const tables" and the handler
for this join is never "opened" via handler::ha_open.

When mysql_derived_fill() is called for the next group of results, this
unopened handler is not taken into account.

reviewed by Igor Babaev (igor@mariadb.com)