sql/sql_list.h:684: void ilink::assert_linked(): Assertion `prev != 0 && next != 0' failed.

Assert hit during RQG testing on

    origin/bb-10.2-thiru 0b91f74906c8dcbcc1dac486fcc66c1e9c0c603a 2019-10-15

    That tree contains fixes which are not yet pushed into the official trees.

    The binary declares to be a "10.2.28-MariaDB-debug-log".

2019-10-15 19:43:26 140072440260352 [Note] sql/mysqld (initiated by: root[root] @ localhost [127.0.0.1]): Normal shutdown

2019-10-15 19:43:26 140072440260352 [Note] Event Scheduler: Purging the queue. 0 events

2019-10-15 19:44:07 140071969748736 [Note] InnoDB: FTS optimize thread exiting.

mysqld: sql/sql_list.h:684: void ilink::assert_linked(): Assertion `prev != 0 && next != 0' failed.

191015 19:44:07 [ERROR] mysqld got signal 6 ;

...

Aborted (core dumped)

gdb -c <core> <binary>

(gdb) bt

#0  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:58

#1  0x00007f655540837a in __GI_abort () at abort.c:89

#2  0x00007f65553feb47 in __assert_fail_base (fmt=<optimized out>, assertion=assertion@entry=0x564e7118ce4a "prev != 0 && next != 0", file=file@entry=0x564e7118ce10 "sql/sql_list.h",

    line=line@entry=684, function=function@entry=0x564e71196db0 <ilink::assert_linked()::__PRETTY_FUNCTION__> "void ilink::assert_linked()") at assert.c:92

#3  0x00007f65553febf2 in __GI___assert_fail (assertion=0x564e7118ce4a "prev != 0 && next != 0", file=0x564e7118ce10 "sql/sql_list.h", line=684,

    function=0x564e71196db0 <ilink::assert_linked()::__PRETTY_FUNCTION__> "void ilink::assert_linked()") at assert.c:101

#4  0x0000564e705f3fe3 in ilink::assert_linked (this=0x7f64f0000a98) at sql/sql_list.h:684

#5  0x0000564e705f520f in unlink_not_visible_thd (thd=0x7f64f0000a98) at sql/sql_class.h:4531

#6  0x0000564e7068763c in destroy_thd (thd=0x7f64f0000a98) at sql/sql_class.cc:4475

#7  0x0000564e70b4cd03 in innobase_destroy_background_thd (thd=0x7f64f0000a98) at storage/innobase/handler/ha_innodb.cc:1689

#8  0x0000564e70d034e8 in srv_worker_thread (arg=0x0) at storage/innobase/srv/srv0srv.cc:2646

#9  0x00007f65560476da in start_thread (arg=0x7f6509ffb700) at pthread_create.c:456

#10 0x00007f65554d9d7f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:105

(gdb) quit

I have never hit that assert in history at all.

During the my testing campaign ~ 1500 RQG tests were executed and only one showed the problem above.

Some quite similar looking bug is 

    MDEV-11693 Assertion `prev != 0 && next != 0' failed in ilink::assert_linked upon shutdown with certain values of innodb_spin_wait_delay

fixed ~ 2017-01-03.