MSAN errors upon using DEFAULT of datetime column

CREATE TABLE t (a DATETIME DEFAULT current_timestamp);

SELECT * FROM t WHERE DEFAULT(a) IS NOT NULL;

DROP TABLE t;

==2018431==WARNING: MemorySanitizer: use-of-uninitialized-value

    #0 0x560c41b95d9b in JOIN::optimize_inner() /data/bld/main-msan/sql/sql_select.cc:2473:71

    #1 0x560c41b84a0c in JOIN::optimize() /data/bld/main-msan/sql/sql_select.cc:2006:10

    #2 0x560c41b6556a in mysql_select(THD*, TABLE_LIST*, List<Item>&, Item*, unsigned int, st_order*, st_order*, Item*, st_order*, unsigned long long, select_result*, st_select_lex_unit*, st_select_lex*) /data/bld/main-msan/sql/sql_select.cc:5370:19

    #3 0x560c41b64424 in handle_select(THD*, LEX*, select_result*, unsigned long long) /data/bld/main-msan/sql/sql_select.cc:634:10

    #4 0x560c41a4c156 in execute_sqlcom_select(THD*, TABLE_LIST*) /data/bld/main-msan/sql/sql_parse.cc:6166:12

    #5 0x560c41a2f8fe in mysql_execute_command(THD*, bool) /data/bld/main-msan/sql/sql_parse.cc:3954:12

    #6 0x560c41a182b9 in mysql_parse(THD*, char*, unsigned int, Parser_state*) /data/bld/main-msan/sql/sql_parse.cc:7882:18

    #7 0x560c41a0e71a in dispatch_command(enum_server_command, THD*, char*, unsigned int, bool) /data/bld/main-msan/sql/sql_parse.cc:1877:7

    #8 0x560c41a19a16 in do_command(THD*, bool) /data/bld/main-msan/sql/sql_parse.cc:1416:17

    #9 0x560c420af5ce in do_handle_one_connection(CONNECT*, bool) /data/bld/main-msan/sql/sql_connect.cc:1414:11

    #10 0x560c420aebbc in handle_one_connection /data/bld/main-msan/sql/sql_connect.cc:1326:5

    #11 0x560c434b401f in pfs_spawn_thread /data/bld/main-msan/storage/perfschema/pfs.cc:2198:3

    #12 0x7f90e1bc91c3 in start_thread nptl/pthread_create.c:442:8

    #13 0x7f90e1c4985b in clone3 misc/../sysdeps/unix/sysv/linux/x86_64/clone3.S:81

  Uninitialized value was stored to memory at

    #0 0x560c41c794d3 in Item::remove_eq_conds(THD*, Item::cond_result*, bool) /data/bld/main-msan/sql/sql_select.cc

  Memory was marked as uninitialized

    #0 0x560c4141c81d in __msan_allocated_memory (/share8t/bld/main-msan/sql/mariadbd+0x95e81d) (BuildId: 93a182b30110bc464f6e75d324decde4a16d84ca)

    #1 0x560c446bf7e7 in my_malloc /data/bld/main-msan/mysys/my_malloc.c:120:7

SUMMARY: MemorySanitizer: use-of-uninitialized-value /data/bld/main-msan/sql/sql_select.cc:2473:71 in JOIN::optimize_inner()

Exiting