bzr push into mysql-trunk branch (Dmitry.Shulga:4193 to 4194)

[Dmitry Shulga]

 4194 Dmitry Shulga	2012-08-13
      Reverted incorrect changes in Item_func_group_concat::add.

    modified:
      sql/item_sum.cc
 4193 Dmitry Shulga	2012-08-10
      The follow-up for WL#6030.
      
      Added some doxygen-style comments.

    modified:
      sql/field.cc
      sql/field.h
      sql/sql_base.cc
=== modified file 'sql/item_sum.cc'
--- a/sql/item_sum.cc	2012-08-08 14:49:40 +0000
+++ b/sql/item_sum.cc	2012-08-13 07:25:09 +0000
@@ -3253,7 +3253,7 @@ bool Item_func_group_concat::add()
     if (!show_item->const_item())
     {
       Field *f= show_item->get_tmp_table_field();
-      if (f->is_real_null())
+      if (f->is_null_in_record((const uchar*) table->record[0]))
         return 0;                               // Skip row if it contains null
     }
   }

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