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.

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.