Setting innodb_redo_log_encrypt to NULL results in a crash

# mysqld options required for replay:  --early-plugin-load=keyring_file.so --keyring_file_data=keyring
mysql> SET @@global.innodb_redo_log_encrypt=NULL;
ERROR 2013 (HY000): Lost connection to MySQL server during query

Core was generated by `/sdc/PS160819-percona-server-5.7.27-30-linux-x86_64-debug/bin/mysqld --no-defau'.
Program terminated with signal 6, Aborted.
#0  0x00007faf82e8b9d1 in __pthread_kill (threadid=<optimized out>, signo=6) at ../nptl/sysdeps/unix/sysv/linux/pthread_kill.c:59
59        val = INTERNAL_SYSCALL (tgkill, err, 3, THREAD_GETMEM (THREAD_SELF, pid),
(gdb) bt
+bt
#0  0x00007faf82e8b9d1 in __pthread_kill (threadid=<optimized out>, signo=6) at ../nptl/sysdeps/unix/sysv/linux/pthread_kill.c:59
#1  0x000000000191c7ca in my_write_core (sig=6) at /sdc/ps-5.7.28-0816_dbg/mysys/stacktrace.c:249
#2  0x0000000001693c3d in handle_fatal_signal (sig=6) at /sdc/ps-5.7.28-0816_dbg/sql/signal_handler.cc:223
#3  <signal handler called>
#4  0x00007faf80f8e2c7 in __GI_raise ([email protected]=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:55
#5  0x00007faf80f8f9b8 in __GI_abort () at abort.c:90
#6  0x0000000001c4a279 in ut_dbg_assertion_failed (expr=0x230720d "0", file=0x2308b58 "/sdc/ps-5.7.28-0816_dbg/storage/innobase/handler/ha_innodb.cc", line=21547) at /sdc/ps-5.7.28-0816_dbg/storage/innobase/ut/ut0dbg.cc:67
#7  0x0000000001a05004 in update_innodb_redo_log_encrypt (thd=0x7faf42419000, var=0x2d643e0 <mysql_sysvar_redo_log_encrypt>, var_ptr=0x2e9cd10 <srv_redo_log_encrypt>, save=0x7faf42427b90) at /sdc/ps-5.7.28-0816_dbg/storage/innobase/handler/ha_innodb.cc:21547
#8  0x000000000157635b in sys_var_pluginvar::global_update (this=0x7faf74fdfab0, thd=0x7faf42419000, var=0x7faf42427b70) at /sdc/ps-5.7.28-0816_dbg/sql/sql_plugin.cc:3844
#9  0x000000000147713c in sys_var::update (this=0x7faf74fdfab0, thd=0x7faf42419000, var=0x7faf42427b70) at /sdc/ps-5.7.28-0816_dbg/sql/set_var.cc:183
#10 0x00000000014788b6 in set_var::update (this=0x7faf42427b70, thd=0x7faf42419000) at /sdc/ps-5.7.28-0816_dbg/sql/set_var.cc:836
#11 0x0000000001478144 in sql_set_variables (thd=0x7faf42419000, var_list=0x7faf4241ba88, free_joins=true) at /sdc/ps-5.7.28-0816_dbg/sql/set_var.cc:672
#12 0x0000000001544896 in mysql_execute_command (thd=0x7faf42419000, first_level=true) at /sdc/ps-5.7.28-0816_dbg/sql/sql_parse.cc:3926
#13 0x000000000154a1af in mysql_parse (thd=0x7faf42419000, parser_state=0x7faf83481440, update_userstat=false) at /sdc/ps-5.7.28-0816_dbg/sql/sql_parse.cc:5905
#14 0x000000000153ec34 in dispatch_command (thd=0x7faf42419000, com_data=0x7faf83481c70, command=COM_QUERY) at /sdc/ps-5.7.28-0816_dbg/sql/sql_parse.cc:1532
#15 0x000000000153da55 in do_command (thd=0x7faf42419000) at /sdc/ps-5.7.28-0816_dbg/sql/sql_parse.cc:1053
#16 0x00000000016705c4 in handle_connection (arg=0x7faf66ad46d0) at /sdc/ps-5.7.28-0816_dbg/sql/conn_handler/connection_handler_per_thread.cc:318
#17 0x000000000194049e in pfs_spawn_thread (arg=0x7faf7f018d20) at /sdc/ps-5.7.28-0816_dbg/storage/perfschema/pfs.cc:2190
#18 0x00007faf82e86dd5 in start_thread (arg=0x7faf83482700) at pthread_create.c:307
#19 0x00007faf8105602d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111