LeakSanitizer/Valgrind errors in Binary_string::real_alloc upon INSERT DELAYED with unique blob and binary log

--source include/have_log_bin.inc

CREATE TABLE t (a TIMESTAMP, b TEXT, UNIQUE(a,b)) ENGINE=MyISAM;

INSERT DELAYED INTO t VALUES ('2012-12-12','foo');

# Cleanup

DROP TABLE t;

Warning: Memory not freed: 48

=================================================================

==1340083==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 48 byte(s) in 1 object(s) allocated from:

    #0 0x7fee5ce17bc8 in malloc (/lib/x86_64-linux-gnu/libasan.so.5+0x10dbc8)

    #1 0x55bac2ed503c in my_malloc /data/src/bb-10.5-release/mysys/my_malloc.c:90

    #2 0x55bac140a593 in Binary_string::real_alloc(unsigned long) /data/src/bb-10.5-release/sql/sql_string.cc:44

    #3 0x55bac0ed6007 in Binary_string::alloc(unsigned long) /data/src/bb-10.5-release/sql/sql_string.h:639

    #4 0x55bac19413f8 in Field_timestamp::val_str(String*, String*) /data/src/bb-10.5-release/sql/field.cc:5377

    #5 0x55bac1a25fff in Item_field::val_str(String*) /data/src/bb-10.5-release/sql/item.cc:3304

    #6 0x55bac13415e2 in Item::val_str() /data/src/bb-10.5-release/sql/item.h:915

    #7 0x55bac1b1c1ad in Item_func_hash::val_int() /data/src/bb-10.5-release/sql/item_func.cc:1784

    #8 0x55bac1a42542 in Item::save_int_in_field(Field*, bool) /data/src/bb-10.5-release/sql/item.cc:6791

    #9 0x55bac176774d in Type_handler_int_result::Item_save_in_field(Item*, Field*, bool) const /data/src/bb-10.5-release/sql/sql_type.cc:4349

    #10 0x55bac1a42728 in Item::save_in_field(Field*, bool) /data/src/bb-10.5-release/sql/item.cc:6801

    #11 0x55bac1526999 in TABLE::update_virtual_fields(handler*, enum_vcol_update_mode) /data/src/bb-10.5-release/sql/table.cc:8666

    #12 0x55bac102fb34 in fill_record(THD*, TABLE*, Field**, List<Item>&, bool, bool) /data/src/bb-10.5-release/sql/sql_base.cc:8807

    #13 0x55bac102fe42 in fill_record_n_invoke_before_triggers(THD*, TABLE*, Field**, List<Item>&, bool, trg_event_type) /data/src/bb-10.5-release/sql/sql_base.cc:8849

    #14 0x55bac10e63e5 in mysql_insert(THD*, TABLE_LIST*, List<Item>&, List<List<Item> >&, List<Item>&, List<Item>&, enum_duplicates, bool, select_result*) /data/src/bb-10.5-release/sql/sql_insert.cc:1061

    #15 0x55bac11b03bd in mysql_execute_command(THD*) /data/src/bb-10.5-release/sql/sql_parse.cc:4624

    #16 0x55bac11c88ed in mysql_parse(THD*, char*, unsigned int, Parser_state*, bool, bool) /data/src/bb-10.5-release/sql/sql_parse.cc:8100

    #17 0x55bac119e7ae in dispatch_command(enum_server_command, THD*, char*, unsigned int, bool, bool) /data/src/bb-10.5-release/sql/sql_parse.cc:1891

    #18 0x55bac119b0ed in do_command(THD*) /data/src/bb-10.5-release/sql/sql_parse.cc:1370

    #19 0x55bac15e5b5c in do_handle_one_connection(CONNECT*, bool) /data/src/bb-10.5-release/sql/sql_connect.cc:1418

    #20 0x55bac15e5375 in handle_one_connection /data/src/bb-10.5-release/sql/sql_connect.cc:1312

    #21 0x55bac2250aa4 in pfs_spawn_thread /data/src/bb-10.5-release/storage/perfschema/pfs.cc:2201

    #22 0x7fee5c74e608 in start_thread /build/glibc-eX1tMB/glibc-2.31/nptl/pthread_create.c:477

SUMMARY: AddressSanitizer: 48 byte(s) leaked in 1 allocation(s).

Warning: Memory not freed: 48

==1340353== 48 bytes in 1 blocks are definitely lost in loss record 1 of 2

==1340353==    at 0x483B7F3: malloc (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)

==1340353==    by 0x173007D: my_malloc (my_malloc.c:90)

==1340353==    by 0xB21590: Binary_string::real_alloc(unsigned long) (sql_string.cc:44)

==1340353==    by 0x8FB254: Binary_string::alloc(unsigned long) (sql_string.h:639)

==1340353==    by 0xD84282: Field_timestamp::val_str(String*, String*) (field.cc:5377)

==1340353==    by 0xDE11DB: Item_field::val_str(String*) (item.cc:3304)

==1340353==    by 0xAD712F: Item::val_str() (item.h:915)

==1340353==    by 0xE4A61A: Item_func_hash::val_int() (item_func.cc:1784)

==1340353==    by 0xDEC195: Item::save_int_in_field(Field*, bool) (item.cc:6791)

==1340353==    by 0xC9342F: Type_handler_int_result::Item_save_in_field(Item*, Field*, bool) const (sql_type.cc:4349)

==1340353==    by 0xDEC24E: Item::save_in_field(Field*, bool) (item.cc:6801)

==1340353==    by 0xB933A2: TABLE::update_virtual_fields(handler*, enum_vcol_update_mode) (table.cc:8666)

==1340353==    by 0x996B39: fill_record(THD*, TABLE*, Field**, List<Item>&, bool, bool) (sql_base.cc:8807)

==1340353==    by 0x996C42: fill_record_n_invoke_before_triggers(THD*, TABLE*, Field**, List<Item>&, bool, trg_event_type) (sql_base.cc:8849)

==1340353==    by 0x9E40B9: mysql_insert(THD*, TABLE_LIST*, List<Item>&, List<List<Item> >&, List<Item>&, List<Item>&, enum_duplicates, bool, select_result*) (sql_insert.cc:1061)

==1340353==    by 0xA39298: mysql_execute_command(THD*) (sql_parse.cc:4624)