Conditional jump depends on uninitialised value for: SELECT NULL UNION geom_expression

SELECT AsText(g) FROM (SELECT NULL AS g UNION SELECT Point(1,1)) AS t1;

==1322== Thread 6:

==1322== Conditional jump or move depends on uninitialised value(s)

==1322==    at 0x90FA60: Field_geom::geometry_type_merge(Field::geometry_type, Field::geometry_type) (field.cc:8605)

==1322==    by 0x959C1E: Item_type_holder::join_types(THD*, Item*) (item.cc:10184)

==1322==    by 0x7962EE: st_select_lex_unit::prepare(THD*, select_result*, unsigned long) (sql_union.cc:635)

==1322==    by 0x680FA4: mysql_derived_prepare(THD*, LEX*, TABLE_LIST*) (sql_derived.cc:726)

==1322==    by 0x67FFD6: mysql_handle_single_derived(LEX*, TABLE_LIST*, unsigned int) (sql_derived.cc:197)

==1322==    by 0x7BE93F: TABLE_LIST::handle_derived(LEX*, unsigned int) (table.cc:7729)

==1322==    by 0x6A10D0: st_select_lex::handle_derived(LEX*, unsigned int) (sql_lex.cc:3886)

==1322==    by 0x6F0311: JOIN::prepare(TABLE_LIST*, unsigned int, Item*, unsigned int, st_order*, bool, st_order*, Item*, st_order*, st_select_lex*, st_select_lex_unit*) (sql_select.cc:712)

==1322==    by 0x6FAA85: mysql_select(THD*, TABLE_LIST*, unsigned int, List<Item>&, Item*, unsigned int, st_order*, st_order*, Item*, st_order*, unsigned long long, select_result*, st_select_lex_unit*, st_select_lex*) (sql_select.cc:3636)

==1322==    by 0x6EF4F6: handle_select(THD*, LEX*, select_result*, unsigned long) (sql_select.cc:373)

==1322==    by 0x6BACE8: execute_sqlcom_select(THD*, TABLE_LIST*) (sql_parse.cc:6431)

==1322==    by 0x6B0A36: mysql_execute_command(THD*) (sql_parse.cc:3448)

==1322==    by 0x6BE670: mysql_parse(THD*, char*, unsigned int, Parser_state*, bool, bool) (sql_parse.cc:7874)

==1322==    by 0x6AC46F: dispatch_command(enum_server_command, THD*, char*, unsigned int, bool, bool) (sql_parse.cc:1812)

==1322==    by 0x6AADD8: do_command(THD*) (sql_parse.cc:1362)

==1322==    by 0x7FA697: do_handle_one_connection(CONNECT*) (sql_connect.cc:1354)

--- a/sql/item.cc

+++ b/sql/item.cc

@@ -10035,7 +10035,8 @@ void Item_cache_row::set_null()

 Item_type_holder::Item_type_holder(THD *thd, Item *item)

   :Item(thd, item),

    Type_handler_hybrid_real_field_type(get_real_type(item)),

-   enum_set_typelib(0)

+   enum_set_typelib(0),

+   geometry_type(Field::GEOM_GEOMETRY)

 {

   DBUG_ASSERT(item->fixed);

   maybe_null= item->maybe_null;

CREATE OR REPLACE TABLE t1 AS SELECT NULL AS g UNION SELECT Point(1,1);