Change in behavior upon creation of unlimited non-unique indexes

create table t1 (f text);

alter table t1 add index ind1 (f);

mysqltest: At line 2: query 'alter table t1 add index ind1 (f)' failed: 1170: BLOB/TEXT column 'f' used in key specification without a key length

alter table t1 add index ind1 (f);

Warnings:

Note	1071	Specified key was too long; max key length is 1000 bytes

show create table t1;

Table	Create Table

t1	CREATE TABLE `t1` (

  `f` text DEFAULT NULL,

  KEY `ind1` (`f`(1000))

) ENGINE=MyISAM DEFAULT CHARSET=latin1