The problem was that when a QUICK_SELECT access method is chosen,
test_if_skip_sort_order() discovered that the index being used
by the quick select will not deliver tuples in sorted order.
In this case test_if_skip_sort_order() tried to change the index
used by the quick select, but it didn't properly set the other
members of the quick select, and especially the range flags of
the ranges in QUICK_SELECT::ranges.

The fix re-invokes the function SQL_SELECT::test_quick_select
to correctly create a valid QUICK_SELECT object.


mysql-test/r/order_by.result:
  Added test results.
mysql-test/t/order_by.test:
  Added test for BUG#7331.
sql/sql_select.cc:
  Fix for BUG#7331.