ALTER TABLE is not enforcing prefix index size limit

--source include/have_innodb.inc

SET @save_format = @@GLOBAL.innodb_file_format;

SET @save_prefix = @@GLOBAL.innodb_large_prefix;

SET GLOBAL innodb_file_format=barracuda;

SET GLOBAL innodb_large_prefix=ON;

CREATE TABLE t1 (c VARCHAR(1024),

c1 CHAR(255) NOT NULL,c2 CHAR(255) NOT NULL,c3 CHAR(255) NOT NULL,

c4 CHAR(255) NOT NULL,c5 CHAR(255) NOT NULL,c6 CHAR(255) NOT NULL,

c7 CHAR(255) NOT NULL,c8 CHAR(255) NOT NULL,c9 CHAR(255) NOT NULL,

ca CHAR(255) NOT NULL,cb CHAR(255) NOT NULL,cc CHAR(255) NOT NULL,

cd CHAR(255) NOT NULL,ce CHAR(255) NOT NULL,cf CHAR(255) NOT NULL,

d0 CHAR(255) NOT NULL,d1 CHAR(255) NOT NULL,d2 CHAR(255) NOT NULL,

d3 CHAR(255) NOT NULL,d4 CHAR(255) NOT NULL,d5 CHAR(255) NOT NULL,

d6 CHAR(255) NOT NULL,d7 CHAR(255) NOT NULL,d8 CHAR(255) NOT NULL,

d9 CHAR(255) NOT NULL,da CHAR(255) NOT NULL,db CHAR(255) NOT NULL,

dc CHAR(255) NOT NULL,dd CHAR(255) NOT NULL,de CHAR(255) NOT NULL,

UNIQUE KEY(c))

ENGINE=InnoDB ROW_FORMAT=DYNAMIC;

INSERT INTO t1 VALUES

(repeat('a',999),'','','','','','','','','','','','','','','','','','','','','','','','','','','','','',''),

(CONCAT(repeat('a',999),'b'),'','','','','','','','','','','','','','','','','','','','','','','','','','','','','','');

--enable_info

ALTER TABLE t1 ROW_FORMAT=REDUNDANT;

--disable_info

SELECT COUNT(*) FROM t1;

CHECK TABLE t1;

DROP TABLE t1;

SET GLOBAL innodb_file_format=@save_format;

SET GLOBAL innodb_large_prefix=@save_prefix;

mysqltest: At line 24: query 'ALTER TABLE t1 ROW_FORMAT=REDUNDANT' failed: 1118: Row size too large. The maximum row size for the used table type, not counting BLOBs, is 8126. This includes storage overhead, check the manual. You have to change some columns to TEXT or BLOBs

mysqltest: At line 24: query 'ALTER TABLE t1 ROW_FORMAT=REDUNDANT' failed: 1709: Index column size too large. The maximum column size is 767 bytes.