Select with a "NULL NOT IN" condition containing complex
subselect from the same table as in the outer select failed
with an assertion.


The failure was caused by a concatenation of circumstances:
1) an inner select was optimized by make_join_statistics to use
   the QUICK_RANGE_SELECT access method (that implies an index
   scan of the table);
2) a subselect was independent (constant) from the outer select;
3) a condition was pushed down into inner select.

During the evaluation of a constant IN expression an optimizer
temporary changed the access method from index scan to table
scan, but an engine handler was already initialized for index
access by make_join_statistics. That caused an assertion.


Unnecessary index initialization has been removed from
the QUICK_RANGE_SELECT::init method (QUICK_RANGE_SELECT::reset
reinvokes this initialization).


mysql-test/r/subselect3.result:
  Added test case for bug #37894.
mysql-test/t/subselect3.test:
  Added test case for bug #37894.
sql/opt_range.cc:
  Bug #37894: Assertion in init_read_record_seq in handler.h line 1444
  
  Unnecessary index initialization has been removed from
  the QUICK_RANGE_SELECT::init method (QUICK_RANGE_SELECT::reset
  reinvokes this initialization).