create or replace table t1 (a int primary key, b int, c int, key(b),key(c)) engine=myisam;
insert into t1 (a) values(1);
set debug_sync='RESET';
connect  con1, localhost, root,,;
connect  con2, localhost, root,,;
connection default;
backup stage start;
backup stage flush;
select * from t1;
a	b	c
1	NULL	NULL
set debug_sync='after_purge_tables SIGNAL parked WAIT_FOR go';
set debug_sync='before_tc_release_table SIGNAL parked2 WAIT_FOR go2';
backup stage BLOCK_DDL;
connection con1;
set debug_sync='now WAIT_FOR parked';
select * from t1;
a	b	c
1	NULL	NULL
set debug_sync='now SIGNAL go';
set debug_sync='now WAIT_FOR parked2';
set debug_sync='before_wait_for_refs SIGNAL waiting WAIT_FOR go3';
drop table t1;;
connection con2;
set debug_sync='now WAIT_FOR waiting';
set debug_sync='now SIGNAL go2';
set debug_sync='now SIGNAL go3';
connection default;
connection con1;
connection default;
disconnect con1;
disconnect con2;
set debug_sync='RESET';