week issue

```
What steps will reproduce the problem?
1. Date.today().set({week: 10}).getWeek();

What is the expected output? What do you see instead?

expected 10, returns 9

What version of the product are you using? On what operating system?

1.0 Alpha-1 2008-05-13 firefox linux

Please provide any additional information below.

```

Original issue reported on code.google.com by `i...@molinodacapo.de` on 5 Jun 2009 at 3:55