Online ALTER TABLE may get stuck in tdc_remove_table

--source include/have_xtradb.inc

CREATE TABLE t1(a INT) ENGINE=InnoDB;

SELECT * FROM t1;

--send SET @@global.table_open_cache=400;

connect(con1, localhost, root);

ALTER TABLE t1 COMMENT='abc';

disconnect con1;

connection default;

--reap

DROP TABLE t1;

diff --git a/sql/table_cache.cc b/sql/table_cache.cc

index 097f37d..b46a620 100644

--- a/sql/table_cache.cc

+++ b/sql/table_cache.cc

@@ -865,6 +865,8 @@ void tdc_release_share(TABLE_SHARE *share)

   }

   mysql_mutex_unlock(&share->tdc.LOCK_table_share);

+  if (!strcmp(share->table_name.str, "t1") && !share->tdc.flushed)

+    sleep(1);

   mysql_mutex_lock(&LOCK_unused_shares);

   mysql_mutex_lock(&share->tdc.LOCK_table_share);

   if (share->tdc.flushed)