Assertion `table_share->tmp_table != NO_TMP_TABLE || m_lock_type != 2' failed in handler::ha_index_read_map upon INSERT into partitioned table

--source include/have_partition.inc

CREATE TABLE t1 (

  a INT NOT NULL AUTO_INCREMENT,

  UNIQUE (a) USING HASH

) ENGINE=MyISAM

PARTITION BY LIST (a) (

  PARTITION p0 VALUES IN (1,3),

  PARTITION p1 VALUES IN (8,4,2)

);

INSERT INTO t1 PARTITION (p1) (a) VALUES (8),(4);

# Cleanup

DROP TABLE t1;

mysqld: /data/src/10.4/sql/handler.cc:2918: int handler::ha_index_read_map(uchar*, const uchar*, key_part_map, ha_rkey_function): Assertion `table_share->tmp_table != NO_TMP_TABLE || m_lock_type != 2' failed.

210208 20:44:55 [ERROR] mysqld got signal 6 ;

#7  0x00007f8baf45cf36 in __GI___assert_fail (assertion=0x556e58df10d8 "table_share->tmp_table != NO_TMP_TABLE || m_lock_type != 2", file=0x556e58defb01 "/data/src/10.4/sql/handler.cc", line=2918, function=0x556e58df1180 "int handler::ha_index_read_map(uchar*, const uchar*, key_part_map, ha_rkey_function)") at assert.c:101

#8  0x0000556e582c2549 in handler::ha_index_read_map (this=0x7f8b98042308, buf=0x7f8b981259c8 "\377\b", key=0x7f8ba942b71f "d\r", keypart_map=18446744073709551615, find_flag=HA_READ_KEY_EXACT) at /data/src/10.4/sql/handler.cc:2918

#9  0x0000556e58b284c8 in ha_partition::handle_unordered_scan_next_partition (this=0x7f8b981a8338, buf=0x7f8b981259c8 "\377\b") at /data/src/10.4/sql/ha_partition.cc:7457

#10 0x0000556e58b22e20 in ha_partition::common_index_read (this=0x7f8b981a8338, buf=0x7f8b981259c8 "\377\b", have_start_key=true) at /data/src/10.4/sql/ha_partition.cc:5713

#11 0x0000556e58b2298e in ha_partition::index_read_map (this=0x7f8b981a8338, buf=0x7f8b981259c8 "\377\b", key=0x7f8ba942b71f "d\r", keypart_map=18446744073709551615, find_flag=HA_READ_KEY_EXACT) at /data/src/10.4/sql/ha_partition.cc:5580

#12 0x0000556e582c26ba in handler::ha_index_read_map (this=0x7f8b981a8338, buf=0x7f8b981259c8 "\377\b", key=0x7f8ba942b71f "d\r", keypart_map=18446744073709551615, find_flag=HA_READ_KEY_EXACT) at /data/src/10.4/sql/handler.cc:2922

#13 0x0000556e582cd3ba in check_duplicate_long_entry_key (table=0x7f8b980414a0, h=0x7f8b981a8338, new_rec=0x7f8b981259c8 "\377\b", key_no=0) at /data/src/10.4/sql/handler.cc:6598

#14 0x0000556e582cda87 in check_duplicate_long_entries (table=0x7f8b980414a0, h=0x7f8b981a8338, new_rec=0x7f8b981259c8 "\377\b") at /data/src/10.4/sql/handler.cc:6670

#15 0x0000556e582cddd6 in handler::ha_write_row (this=0x7f8b981a8338, buf=0x7f8b981259c8 "\377\b") at /data/src/10.4/sql/handler.cc:6750

#16 0x0000556e57f06c0b in write_record (thd=0x7f8b98000d90, table=0x7f8b980414a0, info=0x7f8ba942ba70) at /data/src/10.4/sql/sql_insert.cc:2060

#17 0x0000556e57f03a75 in mysql_insert (thd=0x7f8b98000d90, table_list=0x7f8b980135b0, fields=..., values_list=..., update_fields=..., update_values=..., duplic=DUP_ERROR, ignore=false) at /data/src/10.4/sql/sql_insert.cc:1078

#18 0x0000556e57f52672 in mysql_execute_command (thd=0x7f8b98000d90) at /data/src/10.4/sql/sql_parse.cc:4571

#19 0x0000556e57f5e0ab in mysql_parse (thd=0x7f8b98000d90, rawbuf=0x7f8b98013458 "INSERT INTO t1 PARTITION (p1) (a) VALUES (8),(4)", length=48, parser_state=0x7f8ba942c550, is_com_multi=false, is_next_command=false) at /data/src/10.4/sql/sql_parse.cc:7958

#20 0x0000556e57f4a3d3 in dispatch_command (command=COM_QUERY, thd=0x7f8b98000d90, packet=0x7f8b980087b1 "INSERT INTO t1 PARTITION (p1) (a) VALUES (8),(4)", packet_length=48, is_com_multi=false, is_next_command=false) at /data/src/10.4/sql/sql_parse.cc:1855

#21 0x0000556e57f48c3b in do_command (thd=0x7f8b98000d90) at /data/src/10.4/sql/sql_parse.cc:1373

#22 0x0000556e580d804b in do_handle_one_connection (connect=0x556e5a65fab0) at /data/src/10.4/sql/sql_connect.cc:1412

#23 0x0000556e580d7d94 in handle_one_connection (arg=0x556e5a65fab0) at /data/src/10.4/sql/sql_connect.cc:1316

#24 0x0000556e58af958c in pfs_spawn_thread (arg=0x556e5a5b24e0) at /data/src/10.4/storage/perfschema/pfs.cc:1869

#25 0x00007f8bafcdd609 in start_thread (arg=<optimized out>) at pthread_create.c:477

#26 0x00007f8baf548293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95