Assertion `thd->transaction.stmt.is_empty() || thd->in_sub_stmt || (thd->state_flags & Open_tables_state::BACKUPS_AVAIL)' failed in close_thread_tables

--source include/have_innodb.inc

CREATE TABLE t1 (i INT) ENGINE=InnoDB;

CREATE TABLE t2 (i INT) ENGINE=Aria;

FLUSH TABLE t1, t2 FOR EXPORT;

# Cleanup

UNLOCK TABLES;

DROP TABLE t1, t2;

mysqld: /data/src/10.1/sql/sql_base.cc:935: void close_thread_tables(THD*): Assertion `thd->transaction.stmt.is_empty() || thd->in_sub_stmt || (thd->state_flags & Open_tables_state::BACKUPS_AVAIL)' failed.

170816 16:47:59 [ERROR] mysqld got signal 6 ;

#7  0x00007faed190cee2 in __assert_fail () from /lib/x86_64-linux-gnu/libc.so.6

#8  0x0000562f47a0e65e in close_thread_tables (thd=0x7faec83c7070) at /data/src/10.1/sql/sql_base.cc:934

#9  0x0000562f47be06cc in flush_tables_with_read_lock (thd=0x7faec83c7070, all_tables=0x7faebb8fa170) at /data/src/10.1/sql/sql_reload.cc:593

#10 0x0000562f47a7fcc1 in mysql_execute_command (thd=0x7faec83c7070) at /data/src/10.1/sql/sql_parse.cc:4829

#11 0x0000562f47a86f2b in mysql_parse (thd=0x7faec83c7070, rawbuf=0x7faebb8fa088 "FLUSH TABLE t1, t2 FOR EXPORT", length=29, parser_state=0x7faed3bee5e0) at /data/src/10.1/sql/sql_parse.cc:7344

#12 0x0000562f47a75e8a in dispatch_command (command=COM_QUERY, thd=0x7faec83c7070, packet=0x7faeca319071 "FLUSH TABLE t1, t2 FOR EXPORT", packet_length=29) at /data/src/10.1/sql/sql_parse.cc:1484

#13 0x0000562f47a74c27 in do_command (thd=0x7faec83c7070) at /data/src/10.1/sql/sql_parse.cc:1106

#14 0x0000562f47bacfa1 in do_handle_one_connection (thd_arg=0x7faec83c7070) at /data/src/10.1/sql/sql_connect.cc:1349

#15 0x0000562f47bacd05 in handle_one_connection (arg=0x7faec83c7070) at /data/src/10.1/sql/sql_connect.cc:1261

#16 0x0000562f47f64cf2 in pfs_spawn_thread (arg=0x7faeca2e2970) at /data/src/10.1/storage/perfschema/pfs.cc:1860

#17 0x00007faed387e494 in start_thread (arg=0x7faed3befb00) at pthread_create.c:333

#18 0x00007faed19c993f in clone () from /lib/x86_64-linux-gnu/libc.so.6