Bug #56783 Modify column name will recreate table

Description:
In 5.1.34/40, I change a column name will not recreate table,
But in 5.1.46sp1, It will.
This function is disable? Or a bug?

In 5.1.34
create table a(id int unsigned not null primary key auto_increment, info varchar(32), test varchar(32));
insert into a...... //add data
*************************** 1. row ***************************
       Table: a
Create Table: CREATE TABLE `a` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `info` varchar(32) DEFAULT NULL,
  `test` varchar(32) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1015 DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

alter  table a change test test1 varchar(32);
Query OK, 0 rows affected (0.00 sec)
Records: 0  Duplicates: 0  Warnings: 0

But in 5.1.46sp1:
create table a(id int unsigned not null primary key auto_increment, info varchar(32), test varchar(32));
insert into a...... //add data
*************************** 1. row ***************************
       Table: a
Create Table: CREATE TABLE `a` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `info` varchar(32) DEFAULT NULL,
  `test` varchar(32) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1015 DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

alter  table a change test test1 varchar(32);
Query OK, 512 rows affected (0.38 sec)
Records: 512  Duplicates: 0  Warnings: 0

How to repeat:
In 5.1.34
create table a(id int unsigned not null primary key auto_increment, info varchar(32), test varchar(32));
insert into a...... //add data
*************************** 1. row ***************************
       Table: a
Create Table: CREATE TABLE `a` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `info` varchar(32) DEFAULT NULL,
  `test` varchar(32) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1015 DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

alter  table a change test test1 varchar(32);
Query OK, 0 rows affected (0.00 sec)
Records: 0  Duplicates: 0  Warnings: 0

But in 5.1.46sp1:
create table a(id int unsigned not null primary key auto_increment, info varchar(32), test varchar(32));
insert into a...... //add data
*************************** 1. row ***************************
       Table: a
Create Table: CREATE TABLE `a` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `info` varchar(32) DEFAULT NULL,
  `test` varchar(32) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1015 DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

alter  table a change test test1 varchar(32);
Query OK, 512 rows affected (0.38 sec)
Records: 512  Duplicates: 0  Warnings: 0

Please do not submit the same bug more than once. An existing bug report already describes this very problem. Even if you feel that your issue is somewhat different, the resolution is likely
to be the same. Because of this, we hope you add your comments to the original bug instead.

Thank you for your interest in MySQL.

Duplicate of bug #57832