RETURNS RANDOM DATA
     
When Loose Index Scan Range access is used, MySQL execution needs
to copy non-aggregated fields. end_send() checked if this was
necessary by checking if join_tab->select->quick had type
QS_TYPE_GROUP_MIN_MAX.
      
In this bug, however, MySQL created a sort index to sort the rows
read from this range access method. Thus, instead of having a
join_tab->select->quick we had a
join_tab->filesort->select->quick. The fix is to also check if
the LIS range access method was used as input to filesort and if
so perform copy_fields.
      
Filesort is used in this case because MySQL does not trust 
quoted int to give exact matches. See
test_if_equality_guarantees_uniqueness(). We may want to remove
this restriction. See bug 15920635.