Unexpected ER_LOCK_WAIT_TIMEOUT and result after timeout, assertion failure err != DB_DUPLICATE_KEY

--source include/have_partition.inc

--source include/have_innodb.inc

CREATE TABLE t1 (pk int primary key) ENGINE=InnoDB;

CREATE TABLE t2 (pk int primary key) ENGINE=InnoDB;

--connect (con1,localhost,root,,test)

START TRANSACTION;

INSERT INTO t2 (pk) VALUES (1);

SAVEPOINT sp;

INSERT INTO t1 (pk) VALUES (1);

ROLLBACK TO SAVEPOINT sp;

--connection default

SET innodb_lock_wait_timeout= 1;

--error ER_LOCK_WAIT_TIMEOUT

ALTER TABLE t1 PARTITION BY HASH(pk);

SHOW CREATE TABLE t1;

--connection con1

COMMIT;

--connection default

ALTER TABLE t2 PARTITION BY HASH(pk);

# Cleanup

--disconnect con1

--connection default

DROP TABLE t1, t2;

--error ER_LOCK_WAIT_TIMEOUT

ALTER TABLE t1 PARTITION BY HASH(pk);

ERROR HY000: Lock wait timeout exceeded; try restarting transaction

ALTER TABLE t1 PARTITION BY HASH(pk);

ERROR HY000: Lock wait timeout exceeded; try restarting transaction

SHOW CREATE TABLE t1;

Table	Create Table

t1	CREATE TABLE `t1` (

  `pk` int(11) NOT NULL,

  PRIMARY KEY (`pk`)

) ENGINE=InnoDB DEFAULT CHARSET=latin1

 PARTITION BY HASH (`pk`)

mysqltest: At line 26: query 'ALTER TABLE t2 PARTITION BY HASH(pk)' failed: ER_TABLE_EXISTS_ERROR (1050): Table './test/#sql-backup-3ea389-4' already exists

mariadbd: /data/src/10.6/storage/innobase/row/row0mysql.cc:2962: dberr_t row_rename_table_for_mysql(const char*, const char*, trx_t*, bool): Assertion `err != DB_DUPLICATE_KEY' failed.

210612 20:24:56 [ERROR] mysqld got signal 6 ;

#7  0x00007f81ceefef36 in __GI___assert_fail (assertion=0x559b433158a5 "err != DB_DUPLICATE_KEY", file=0x559b43313c08 "/data/src/10.6/storage/innobase/row/row0mysql.cc", line=2962, function=0x559b43315778 "dberr_t row_rename_table_for_mysql(const char*, const char*, trx_t*, bool)") at assert.c:101

#8  0x0000559b42b901f5 in row_rename_table_for_mysql (old_name=0x7f81c8141ca0 "test/t2", new_name=0x7f81c8141aa0 "test/#sql-backup-3ea506-4", trx=0x7f81c93f33c0, use_fk=true) at /data/src/10.6/storage/innobase/row/row0mysql.cc:2962

#9  0x0000559b429f6814 in innobase_rename_table (trx=0x7f81c93f33c0, from=0x7f81c81427e0 "./test/t2", to=0x7f81c81429e0 "./test/#sql-backup-3ea506-4", use_fk=true) at /data/src/10.6/storage/innobase/handler/ha_innodb.cc:13423

#10 0x0000559b429de12f in ha_innobase::rename_table (this=0x7f819c018288, from=0x7f81c81427e0 "./test/t2", to=0x7f81c81429e0 "./test/#sql-backup-3ea506-4") at /data/src/10.6/storage/innobase/handler/ha_innodb.cc:13671

#11 0x0000559b425542af in handler::ha_rename_table (this=0x7f819c018288, from=0x7f81c81427e0 "./test/t2", to=0x7f81c81429e0 "./test/#sql-backup-3ea506-4") at /data/src/10.6/sql/handler.cc:5270

#12 0x0000559b422bcfb1 in mysql_rename_table (base=0x559b46095668, old_db=0x7f81c81445e0, old_name=0x7f81c81445f0, new_db=0x7f81c81445e0, new_name=0x7f81c8143140, id=0x7f81c8144680, flags=2) at /data/src/10.6/sql/sql_table.cc:4972

#13 0x0000559b422cd6a1 in mysql_alter_table (thd=0x7f819c000db8, new_db=0x7f819c0059c8, new_name=0x7f819c005de0, create_info=0x7f81c81453e0, table_list=0x7f819c0156b0, alter_info=0x7f81c81452f0, order_num=0, order=0x0, ignore=false, if_exists=false) at /data/src/10.6/sql/sql_table.cc:10521

#14 0x0000559b42381fad in Sql_cmd_alter_table::execute (this=0x7f819c0160f8, thd=0x7f819c000db8) at /data/src/10.6/sql/sql_alter.cc:550

#15 0x0000559b421c9562 in mysql_execute_command (thd=0x7f819c000db8) at /data/src/10.6/sql/sql_parse.cc:5983

#16 0x0000559b421cf708 in mysql_parse (thd=0x7f819c000db8, rawbuf=0x7f819c0155c0 "ALTER TABLE t2 PARTITION BY HASH(pk)", length=36, parser_state=0x7f81c8146480) at /data/src/10.6/sql/sql_parse.cc:8016

#17 0x0000559b421bbb92 in dispatch_command (command=COM_QUERY, thd=0x7f819c000db8, packet=0x7f819c00b879 "", packet_length=36, blocking=true) at /data/src/10.6/sql/sql_parse.cc:1897

#18 0x0000559b421ba537 in do_command (thd=0x7f819c000db8, blocking=true) at /data/src/10.6/sql/sql_parse.cc:1406

#19 0x0000559b42376d71 in do_handle_one_connection (connect=0x559b465ec328, put_in_cache=true) at /data/src/10.6/sql/sql_connect.cc:1410

#20 0x0000559b42376acd in handle_one_connection (arg=0x559b466152a8) at /data/src/10.6/sql/sql_connect.cc:1312

#21 0x0000559b428e5ed9 in pfs_spawn_thread (arg=0x559b465ebe78) at /data/src/10.6/storage/perfschema/pfs.cc:2201

#22 0x00007f81cf416609 in start_thread (arg=<optimized out>) at pthread_create.c:477

#23 0x00007f81cefea293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95