MSAN uninitialized value errors in bcmp / prep_alter_part_table upon re-partitioning by system time

--source include/have_partition.inc

CREATE TABLE t (a INT) WITH SYSTEM VERSIONING PARTITION BY system_time INTERVAL 5 WEEK;

ALTER TABLE t PARTITION BY SYSTEM_TIME INTERVAL 10 WEEK;

# Cleanup

DROP TABLE t;

Uninitialized bytes in MemcmpInterceptorCommon at offset 76 inside [0x70a00000a7b0, 80)

==80544==WARNING: MemorySanitizer: use-of-uninitialized-value

    #0 0x55bdc97ee93e in bcmp (/home/jenkins/10.9/sql/mariadbd+0x81993e)

    #1 0x55bdc9e96b45 in prep_alter_part_table(THD*, TABLE*, Alter_info*, HA_CREATE_INFO*, bool*, bool*) /home/jenkins/10.9/sql/sql_partition.cc:5991:13

    #2 0x55bdca233749 in mysql_alter_table(THD*, st_mysql_const_lex_string const*, st_mysql_const_lex_string const*, Table_specification_st*, TABLE_LIST*, Alter_info*, unsigned int, st_order*, bool, bool) /home/jenkins/10.9/sql/sql_table.cc:10386:9

    #3 0x55bdca4c6d8c in Sql_cmd_alter_table::execute(THD*) /home/jenkins/10.9/sql/sql_alter.cc:557:11

    #4 0x55bdc9e2a7e9 in mysql_execute_command(THD*, bool) /home/jenkins/10.9/sql/sql_parse.cc:5997:26

    #5 0x55bdc9e11d47 in mysql_parse(THD*, char*, unsigned int, Parser_state*) /home/jenkins/10.9/sql/sql_parse.cc:8023:18

    #6 0x55bdc9e067d3 in dispatch_command(enum_server_command, THD*, char*, unsigned int, bool) /home/jenkins/10.9/sql/sql_parse.cc:1894:7

    #7 0x55bdc9e1413f in do_command(THD*, bool) /home/jenkins/10.9/sql/sql_parse.cc:1407:17

    #8 0x55bdca4a2bc6 in do_handle_one_connection(CONNECT*, bool) /home/jenkins/10.9/sql/sql_connect.cc:1416:11

    #9 0x55bdca4a2255 in handle_one_connection /home/jenkins/10.9/sql/sql_connect.cc:1318:5

    #10 0x55bdcb84fc3a in pfs_spawn_thread /home/jenkins/10.9/storage/perfschema/pfs.cc:2201:3

    #11 0x7fcaff7f3608 in start_thread /build/glibc-eX1tMB/glibc-2.31/nptl/pthread_create.c:477:8

    #12 0x7fcaff4f8292 in clone /build/glibc-eX1tMB/glibc-2.31/misc/../sysdeps/unix/sysv/linux/x86_64/clone.S:95

  Uninitialized value was stored to memory at

    #0 0x55bdc97e4359 in __msan_memcpy (/home/jenkins/10.9/sql/mariadbd+0x80f359)

    #1 0x55bdca414cb6 in Vers_part_info::Vers_part_info(Vers_part_info const&) /home/jenkins/10.9/sql/partition_info.h:50:5

    #2 0x55bdca414cb6 in partition_info::get_clone(THD*, bool) /home/jenkins/10.9/sql/partition_info.cc:116:38

  Memory was marked as uninitialized

    #0 0x55bdc97eabee in __msan_allocated_memory (/home/jenkins/10.9/sql/mariadbd+0x815bee)

    #1 0x55bdccad9730 in my_malloc /home/jenkins/10.9/mysys/my_malloc.c:113:7

SUMMARY: MemorySanitizer: use-of-uninitialized-value (/home/jenkins/10.9/sql/mariadbd+0x81993e) in bcmp

commit 92bfc0e8c4bb5c86359c29458d67f3e7836ec18a

Author: Aleksey Midenkov

Date:   Fri May 6 10:45:17 2022 +0300

    MDEV-17554 Auto-create new partition for system versioned tables with history partitioned by INTERVAL/LIMIT

commit 75ede427e429b24001fc55bb284c110875fbf85a

Author: Aleksey Midenkov

Date:   Fri May 6 10:45:17 2022 +0300

    MDEV-27328 Change of SYSTEM_TIME partitioning options is not possible without data copy