Problem:-
When we execute a query which has subquery with GROUP BY, ORDER BY and have a
BLOB column,results a memory leak.

Analysis:-
In case of subquery, which have GROUP BY on BLOB and a ORDER BY on other field
and BLOB is not a key. We allocate a tmp buffer to copy_field to take care of
BLOB value.This copy_field value can have copies of its in two join(objects),
so while freeing this copy_field we have to take care that it is
not deleted twice.
The double deletion of tmp_table_param.copy_field is handled by two patches.

One by Kostja :
revid:sp1r-konstantin@mysql.com-20050627101056-55153
Fix the broken test suite in -debug build.

and other by Oleksandr
revid:sp1r-bell@sanja.is.com.ua-20060118114857-19905
Excluded posibility of tmp_table_param.copy_field double deletion (BUG#14851).

both of this patches are commited in different branch and while
merging they both get placed,but there is no need for Kostja patch as Oleksandr
patch handle this.