Wrong result with outer join, merged derived table and view

CREATE TABLE t1 (

  PostID int(10) unsigned NOT NULL

) DEFAULT CHARSET=utf8;

INSERT INTO t1 (PostID) VALUES (1), (2);

CREATE TABLE t2 (

  VoteID int(10) unsigned NOT NULL PRIMARY KEY AUTO_INCREMENT,

  EntityID int(10) unsigned NOT NULL,

  UserID int(10) unsigned NOT NULL,

  UNIQUE KEY EntityID (EntityID,UserID)

) DEFAULT CHARSET=utf8;

INSERT INTO t2 (EntityID, UserID) VALUES (1,  30), (2, 30);

CREATE VIEW v1 as SELECT t1.*, T.Voted as Voted

FROM 

t1 LEFT JOIN (

  SELECT 1 AS Voted, EntityID 

  FROM t2 

  WHERE t2.UserID = '20' ) AS T 

  ON T.EntityID = t1.PostID

WHERE t1.PostID='1'

LIMIT 1;

SELECT * FROM  v1;

DROP VIEW v1;

DROP TABLE t1,t2;

PostID	Voted

1	1

PostID	Voted

1	NULL