innodb_read_only=ON fails to imply innodb_doublewrite=OFF

-- source include/have_innodb.inc

--let $restart_parameters= --innodb-force-recovery=6

--source include/restart_mysqld.inc

SET GLOBAL innodb_doublewrite=1;

SET GLOBAL innodb_buf_flush_list_now=1;

#0  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50

#1  0x0000153490f70859 in __GI_abort () at abort.c:79

#2  0x0000153490f70729 in __assert_fail_base (fmt=0x153491106588 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=0x55ae63627c44 "!srv_read_only_mode", file=0x55ae63691e10 "/test/mtest/MDEV-33856/11.6_dbg/storage/innobase/buf/buf0dblwr.cc", line=732, function=<optimized out>) at assert.c:92

#3  0x0000153490f81fd6 in __GI___assert_fail (assertion=assertion@entry=0x55ae63627c44 "!srv_read_only_mode", file=file@entry=0x55ae63691e10 "/test/mtest/MDEV-33856/11.6_dbg/storage/innobase/buf/buf0dblwr.cc", line=line@entry=732, function=function@entry=0x55ae63692150 "void buf_dblwr_t::flush_buffered_writes()") at assert.c:101

#4  0x000055ae63008e65 in buf_dblwr_t::flush_buffered_writes (this=0x55ae64723e20 <buf_dblwr>) at /test/mtest/MDEV-33856/11.6_dbg/storage/innobase/buf/buf0dblwr.cc:732

#5  0x000055ae630174d9 in buf_flush_list_space (space=space@entry=0x55ae663b7ba8, n_flushed=n_flushed@entry=0x0) at /test/mtest/MDEV-33856/11.6_dbg/storage/innobase/buf/buf0flu.cc:1689

#6  0x000055ae62d36154 in buf_flush_list_now_set (save=<optimized out>) at /test/mtest/MDEV-33856/11.6_dbg/storage/innobase/handler/ha_innodb.cc:18227

#7  0x000055ae62695d87 in sys_var_pluginvar::global_update (this=0x55ae662a72a0, thd=0x153478000d48, var=0x153478018e50) at /test/mtest/MDEV-33856/11.6_dbg/sql/sql_plugin.cc:3687

#8  0x000055ae62576024 in sys_var::update (this=0x55ae662a72a0, thd=0x153478000d48, var=0x153478018e50) at /test/mtest/MDEV-33856/11.6_dbg/sql/set_var.cc:210

#9  0x000055ae62576567 in set_var::update (this=<optimized out>, thd=<optimized out>) at /test/mtest/MDEV-33856/11.6_dbg/sql/set_var.cc:868

#10 0x000055ae62577922 in sql_set_variables (thd=thd@entry=0x153478000d48, var_list=var_list@entry=0x1534780061d8, free=free@entry=true) at /test/mtest/MDEV-33856/11.6_dbg/sql/set_var.cc:750

#11 0x000055ae6267371a in mysql_execute_command (thd=thd@entry=0x153478000d48, is_called_from_prepared_stmt=is_called_from_prepared_stmt@entry=false) at /test/mtest/MDEV-33856/11.6_dbg/sql/sql_parse.cc:4841

#12 0x000055ae6266210c in mysql_parse (thd=thd@entry=0x153478000d48, rawbuf=<optimized out>, length=<optimized out>, parser_state=parser_state@entry=0x1534897ef270) at /test/mtest/MDEV-33856/11.6_dbg/sql/sql_parse.cc:7868

#13 0x000055ae6267916e in dispatch_command (command=command@entry=COM_QUERY, thd=thd@entry=0x153478000d48, packet=packet@entry=0x15347800b2d9 "SET GLOBAL innodb_buf_flush_list_now=1", packet_length=packet_length@entry=38, blocking=blocking@entry=true) at /test/mtest/MDEV-33856/11.6_dbg/sql/sql_class.h:1638

#14 0x000055ae6267bc71 in do_command (thd=0x153478000d48, blocking=blocking@entry=true) at /test/mtest/MDEV-33856/11.6_dbg/sql/sql_parse.cc:1405

#15 0x000055ae6280492d in do_handle_one_connection (connect=<optimized out>, connect@entry=0x55ae667c3f08, put_in_cache=put_in_cache@entry=true) at /test/mtest/MDEV-33856/11.6_dbg/sql/sql_connect.cc:1448

#16 0x000055ae62804eee in handle_one_connection (arg=arg@entry=0x55ae667c3f08) at /test/mtest/MDEV-33856/11.6_dbg/sql/sql_connect.cc:1350

#17 0x000055ae62c8d286 in pfs_spawn_thread (arg=0x55ae66743de8) at /test/mtest/MDEV-33856/11.6_dbg/storage/perfschema/pfs.cc:2201

#18 0x0000153491481609 in start_thread (arg=<optimized out>) at pthread_create.c:477

#19 0x000015349106d133 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95