containing a select statement that uses an aggregating IN subquery.
Added a parameter to the function fix_prepare_information 
to restore correctly the having clause for the second execution.
Saved andor structure of the having conditions at the proper moment
before any calls of split_sum_func2 that could modify the having structure
adding new Item_ref objects. (These additions, are produced not with 
the statement mem_root, but rather with the execution mem_root.)