IYYY: unexpected behaviour

Hi,

SELECT to_char( '2006-01-01'::timestamp, 'IYYY-MM-DD' ) AS strange,

to_char( '2006-01-02'::timestamp, 'IYYY-MM-DD' ),

to_char( '2006-01-01'::timestamp, 'YYYY-MM-DD' );

does produce unexpected result for column 'strange':

strange | to_char | to_char

------------+------------+------------

2005-01-01 | 2006-01-02 | 2006-01-01

(1 row)

Is this a bug?

select version();

"PostgreSQL 8.2beta1 on i686-pc-mingw32, compiled by GCC gcc.exe (GCC)
3.4.2 (mingw-special)"