Fix for MIX and MAX. Item must be checked against binary().

sql/item_sum.cc

@@ -188,7 +188,7 @@ Item_sum_hybrid::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
     max_length=float_length(decimals);
   else
   {
-    str_cmp_function= binary() ? stringcmp : sortcmp;
+    str_cmp_function= item->binary() ? stringcmp : sortcmp;
     max_length=item->max_length;
   }
   decimals=item->decimals;