We have next problem here:
active_index is wrong in the subselect's handler on the second val_int() call.
Optimizer sees that we can use index-read for that kind of condition,
and matching_cond() (sql/opt_sum.cc) doesn't. I suspect, proper solution is
to add appropriate code to the matching_cond() but now just added
missed initialization.


mysql-test/r/subselect.result:
  Appropriate test result
mysql-test/t/subselect.test:
  Test case added
sql/records.cc:
  index's initialization added