Valgrind warnings (Conditional jump or move depends on uninitialised value) in remove_eq_conds on time functions with NULL argument in WHERE

SELECT 1 FROM DUAL WHERE HOUR( TIMEDIFF( NULL, '12:12:12' ) );

==27107== Conditional jump or move depends on uninitialised value(s)

==27107==    at 0x72D8BF: remove_eq_conds(THD*, Item*, Item::cond_result*) (sql_select.cc:13333)

==27107==    by 0x72CE8B: optimize_cond(JOIN*, Item*, List<TABLE_LIST>*, bool, Item::cond_result*, COND_EQUAL**) (sql_select.cc:13127)

==27107==    by 0x70D639: JOIN::optimize() (sql_select.cc:1019)

==27107==    by 0x7149CE: mysql_select(THD*, Item***, 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:2976)

==27107==    by 0x70B40E: handle_select(THD*, st_lex*, select_result*, unsigned long) (sql_select.cc:288)

==27107==    by 0x6968A2: execute_sqlcom_select(THD*, TABLE_LIST*) (sql_parse.cc:5172)

==27107==    by 0x68D661: mysql_execute_command(THD*) (sql_parse.cc:2305)

==27107==    by 0x69931C: mysql_parse(THD*, char*, unsigned int, char const**) (sql_parse.cc:6173)

==27107==    by 0x68AE05: dispatch_command(enum_server_command, THD*, char*, unsigned int) (sql_parse.cc:1243)

==27107==    by 0x68A0A3: do_command(THD*) (sql_parse.cc:923)

==27107==    by 0x686AFE: handle_one_connection (sql_connect.cc:1231)

==27107==    by 0x548DE99: start_thread (pthread_create.c:308)

==27107==    by 0x5F9ACBC: clone (clone.S:112)

revision-id: sergii@pisem.net-20130318074424-frdzldas283cvx1w

revno: 3638

branch-nick: 5.3