ALTER TABLE fails when a stored virtual column is dropped and added

--source include/have_innodb.inc

--source include/have_debug_sync.inc

create table t1 (a char(9), b char(9) as (a) stored) engine=InnoDB;

insert into t1 values ('foobar');

--send

  set debug_sync= 'now wait_for downgraded';

--connect(con1,localhost,root,,)

set debug_sync= 'alter_table_online_downgraded signal downgraded wait_for goforit';

--send 

alter ignore table t1 drop b, add b char(3) as (a) stored, algorithm=copy, lock=none

--connection default

--reap

update t1 set a = 'foobarqux';

set debug_sync= 'now signal goforit';

--connection con1

--reap  

# Cleanup

drop table t1;

set debug_sync= reset;