Anyone else frustrated with days_in_month?

I posted a patch (my first) and I was looking for some kind of input on it from the community. http://dev.rubyonrails.org/ticket/10799

What did I do right?
What did I do wrong?

How much do you love it?

I find this very userful, I used days_in_month in my app, but i did
not noticed it does not use current year I thougth it was obvious.

Change of code you made seems simple, but I am not able to say whether
it is done right.