Unexpected warning emitted when inserting into a float number

The following sequence of commands produces an unexpected warning in MariaDB 5.2/5.5:

MariaDB [test]> CREATE TABLE t1 (f FLOAT);
Query OK, 0 rows affected (0.00 sec)

MariaDB [test]> INSERT INTO t1 VALUES ('1.');
Query OK, 1 row affected, 1 warning (0.00 sec)

MariaDB [test]> SHOW WARNINGS;
+---------+------+----------------------------------------+
| Level | Code | Message |
+---------+------+----------------------------------------+
| Warning | 1265 | Data truncated for column 'f' at row 1 |
+---------+------+----------------------------------------+
1 row in set (0.00 sec)

See also bug #63704 from bugs.mysql.com