results in server crash 
 
check_group_min_max_predicates() assumed the input condition 
item to be one of COND_ITEM, SUBSELECT_ITEM, or FUNC_ITEM. 
Since a condition of the form "field" is also a valid condition 
equivalent to "field <> 0", using such a condition in a query 
where the loose index scan was chosen resulted in a debug 
assertion failure. 
 
Fixed by handling conditions of the FIELD_ITEM type in 
check_group_min_max_predicates().