Change text column collation unnecessarily requires ALGORITHM=COPY

--source include/have_innodb.inc

CREATE TABLE t1 (c1 INT PRIMARY KEY, c2 INT,

                 c3 TEXT CHARACTER SET utf8 COLLATE utf8_bin not null,

                 index(c3))ENGINE=InnoDB STATS_PERSISTENT=0;

SHOW CREATE TABLE t1;

ALTER TABLE t1 CHANGE c3 c3 TEXT CHARACTER SET utf8 COLLATE utf8_unicode_ci, algorithm=inplace;

DROP TABLE t1;

mysqltest: At line 6: query 'ALTER TABLE t1 CHANGE c3 c3 TEXT CHARACTER SET utf8 COLLATE utf8_unicode_ci, algorithm=inplace' failed: ER_ALTER_OPERATION_NOT_SUPPORTED_REASON (1846): ALGORITHM=INPLACE is not supported. Reason: Cannot change column type. Try ALGORITHM=COPY