connection attempts sometimes hang on waiting FLUSH TABLES

When FLUSH TABLES has to wait for another query to finish, I see the weird effect that two out of three client connect attempts hang until FLUSH has finished, while one out of three attempts succeed.

How to reproduce:

• first session

USE test;

CREATE TABLE t1(id int primary key);

INSERT INTO t1 VALUES(1);

SELECT id, SLEEP(3600) FROM t1;

• second session

FLUSH TABLES;

• third terminal just trying to connect, as root, with

mysql -A

The weird effect is that two attempts in a row hang and need to be terminated with CTRL-C, then one attempt succeeds, then the next two hang again, then one succeeds, and so on ...