Assertion `0' failed in mysql_execute_command with SET STATEMENT

--source include/have_innodb.inc

CREATE TABLE tx (pk INT PRIMARY KEY) ENGINE=InnoDB;

CREATE TABLE t1 (pk INT, a INT, PRIMARY KEY (pk), KEY (a), FOREIGN KEY (a) REFERENCES tx (pk)) ENGINE=InnoDB;

--error ER_FK_COLUMN_CANNOT_DROP

SET STATEMENT FOREIGN_KEY_CHECKS=OFF FOR ALTER TABLE t1 DROP a;

# Cleanup

DROP TABLE t1, tx;

mysqld: /data/src/10.3/sql/sql_parse.cc:3546: int mysql_execute_command(THD*): Assertion `0' failed.

190228 21:50:42 [ERROR] mysqld got signal 6 ;

#7  0x00007f7180be8ee2 in __assert_fail () from /lib/x86_64-linux-gnu/libc.so.6

#8  0x000055d30ed3bd74 in mysql_execute_command (thd=0x7f7130000b00) at /data/src/10.3/sql/sql_parse.cc:3546

#9  0x000055d30ed4a145 in mysql_parse (thd=0x7f7130000b00, rawbuf=0x7f7130014cf8 "SET STATEMENT FOREIGN_KEY_CHECKS=OFF FOR ALTER TABLE t1 DROP a", length=62, parser_state=0x7f7175efb5f0, is_com_multi=false, is_next_command=false) at /data/src/10.3/sql/sql_parse.cc:8095

#10 0x000055d30ed372f9 in dispatch_command (command=COM_QUERY, thd=0x7f7130000b00, packet=0x7f71301622a1 "SET STATEMENT FOREIGN_KEY_CHECKS=OFF FOR ALTER TABLE t1 DROP a", packet_length=62, is_com_multi=false, is_next_command=false) at /data/src/10.3/sql/sql_parse.cc:1854

#11 0x000055d30ed35cd1 in do_command (thd=0x7f7130000b00) at /data/src/10.3/sql/sql_parse.cc:1396

#12 0x000055d30ee9e41f in do_handle_one_connection (connect=0x55d311aa1c30) at /data/src/10.3/sql/sql_connect.cc:1403

#13 0x000055d30ee9e1a3 in handle_one_connection (arg=0x55d311aa1c30) at /data/src/10.3/sql/sql_connect.cc:1309

#14 0x000055d30f33a8b3 in pfs_spawn_thread (arg=0x55d311ae34f0) at /data/src/10.3/storage/perfschema/pfs.cc:1862

#15 0x00007f71828bf494 in start_thread (arg=0x7f7175efc700) at pthread_create.c:333

#16 0x00007f7180ca593f in clone () from /lib/x86_64-linux-gnu/libc.so.6