Assertion failure err != DB_DUPLICATE_KEY or unexpected ER_TABLE_EXISTS_ERROR (backport MDEV-25902)

--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

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;

mysqltest: At line 24: query 'ALTER TABLE t2 PARTITION BY HASH(pk)' failed: 1050: Table './test/#sql2-1f48cb-9' already exists

mysqld: /data/src/10.3/storage/innobase/row/row0mysql.cc:4350: dberr_t row_rename_table_for_mysql(const char*, const char*, trx_t*, bool, bool): Assertion `err != DB_DUPLICATE_KEY' failed.

210702 10:36:26 [ERROR] mysqld got signal 6 ;

#6  0x00007fcd504c0729 in __assert_fail_base (fmt=0x7fcd50656588 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=0x556d4205de45 "err != DB_DUPLICATE_KEY", file=0x556d4205b0c8 "/data/src/10.3/storage/innobase/row/row0mysql.cc", line=4350, function=<optimized out>) at assert.c:92

#7  0x00007fcd504d1f36 in __GI___assert_fail (assertion=0x556d4205de45 "err != DB_DUPLICATE_KEY", file=0x556d4205b0c8 "/data/src/10.3/storage/innobase/row/row0mysql.cc", line=4350, function=0x556d4205dcc8 "dberr_t row_rename_table_for_mysql(const char*, const char*, trx_t*, bool, bool)") at assert.c:101

#8  0x0000556d418bb844 in row_rename_table_for_mysql (old_name=0x7fcd4953e810 "test/t2", new_name=0x7fcd4953e610 "test/#sql2-1f492f-9", trx=0x7fcd4a043228, commit=true, use_fk=true) at /data/src/10.3/storage/innobase/row/row0mysql.cc:4350

#9  0x0000556d417390ad in innobase_rename_table (trx=0x7fcd4a043228, from=0x7fcd4953f7c0 "./test/t2", to=0x7fcd4953f9d0 "./test/#sql2-1f492f-9", commit=true) at /data/src/10.3/storage/innobase/handler/ha_innodb.cc:13486

#10 0x0000556d417209b3 in ha_innobase::rename_table (this=0x7fccfc015578, from=0x7fcd4953f7c0 "./test/t2", to=0x7fcd4953f9d0 "./test/#sql2-1f492f-9") at /data/src/10.3/storage/innobase/handler/ha_innodb.cc:13684

#11 0x0000556d414dff0f in handler::ha_rename_table (this=0x7fccfc015578, from=0x7fcd4953f7c0 "./test/t2", to=0x7fcd4953f9d0 "./test/#sql2-1f492f-9") at /data/src/10.3/sql/handler.cc:4696

#12 0x0000556d4128a1b1 in mysql_rename_table (base=0x556d43dd3060, old_db=0x7fcd495408b0, old_name=0x7fcd495408c0, new_db=0x7fcd495408b0, new_name=0x7fcd49540170, flags=2) at /data/src/10.3/sql/sql_table.cc:5611

#13 0x0000556d41297463 in mysql_alter_table (thd=0x7fccfc000d90, new_db=0x7fccfc005488, new_name=0x7fccfc005870, create_info=0x7fcd49541490, table_list=0x7fccfc012bd8, alter_info=0x7fcd495413d0, order_num=0, order=0x0, ignore=false) at /data/src/10.3/sql/sql_table.cc:10263

#14 0x0000556d4132798c in Sql_cmd_alter_table::execute (this=0x7fccfc013598, thd=0x7fccfc000d90) at /data/src/10.3/sql/sql_alter.cc:512

#15 0x0000556d411b0e1b in mysql_execute_command (thd=0x7fccfc000d90) at /data/src/10.3/sql/sql_parse.cc:6075

#16 0x0000556d411b64da in mysql_parse (thd=0x7fccfc000d90, rawbuf=0x7fccfc012ae8 "ALTER TABLE t2 PARTITION BY HASH(pk)", length=36, parser_state=0x7fcd49542530, is_com_multi=false, is_next_command=false) at /data/src/10.3/sql/sql_parse.cc:7870

#17 0x0000556d411a2b97 in dispatch_command (command=COM_QUERY, thd=0x7fccfc000d90, packet=0x7fccfc008f41 "", packet_length=36, is_com_multi=false, is_next_command=false) at /data/src/10.3/sql/sql_parse.cc:1852

#18 0x0000556d411a1537 in do_command (thd=0x7fccfc000d90) at /data/src/10.3/sql/sql_parse.cc:1398

#19 0x0000556d41321822 in do_handle_one_connection (connect=0x556d440df920) at /data/src/10.3/sql/sql_connect.cc:1403

#20 0x0000556d4132157e in handle_one_connection (arg=0x556d440df920) at /data/src/10.3/sql/sql_connect.cc:1308

#21 0x0000556d41cf6b09 in pfs_spawn_thread (arg=0x556d440c2780) at /data/src/10.3/storage/perfschema/pfs.cc:1869

#22 0x00007fcd50696609 in start_thread (arg=<optimized out>) at pthread_create.c:477

#23 0x00007fcd505bd293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95