Valgrind warnings on OPTIMIZE MyISAM or Aria TABLE with disabled keys

Syscall param pwrite64(buf) points to uninitialised byte(s)

   at 0x5460A73: ??? (syscall-template.S:82)

   by 0xCD979F: my_pwrite (my_pread.c:145)

   by 0xC03078: inline_mysql_file_pwrite (mysql_file.h:1201)

   by 0xC07CCD: mi_state_info_write (mi_open.c:928)

   by 0xBE9F4E: update_state_info (mi_check.c:4459)

   by 0xBD5A9E: ha_myisam::repair(THD*, st_handler_check_param&, bool) (ha_myisam.cc:1192)

   by 0xBD504E: ha_myisam::optimize(THD*, st_ha_check_opt*) (ha_myisam.cc:1049)

   by 0x7D6C9A: handler::ha_optimize(THD*, st_ha_check_opt*) (handler.cc:3526)

   by 0x72501B: mysql_admin_table(THD*, TABLE_LIST*, st_ha_check_opt*, char const*, thr_lock_type, bool, bool, unsigned int, int (*)(THD*, TABLE_LIST*, st_ha_check_opt*), int (handler::*)(THD*, st_ha_check_opt*), int (*)(THD*, TABLE_LIST*)) (sql_admin.cc:644)

   by 0x7268C4: Optimize_table_statement::execute(THD*) (sql_admin.cc:1056)

   by 0x61743C: mysql_execute_command(THD*) (sql_parse.cc:4453)

   by 0x61A5DE: mysql_parse(THD*, char*, unsigned int, Parser_state*) (sql_parse.cc:5730)

   by 0x60DDF0: dispatch_command(enum_server_command, THD*, char*, unsigned int) (sql_parse.cc:1055)

   by 0x60D0A7: do_command(THD*) (sql_parse.cc:794)

   by 0x715040: do_handle_one_connection(THD*) (sql_connect.cc:1253)

   by 0x714A2B: handle_one_connection (sql_connect.cc:1168)

 Address 0x40c9e2c is on thread 4's stack

CREATE TABLE t1 (a INT, KEY(a)) ENGINE=MyISAM ;

INSERT INTO t1 VALUES (4),(3),(1),(0);

ALTER TABLE t1 DISABLE KEYS;

OPTIMIZE TABLE t1;