Using Picasso to download images, but not download images from redirects

I'm using Picasso to download images from an API that returns default gravatar images for users who don't have one set. However, I want to handle default images on my own without downloading the default avatar provided by the API. The only problem is I have no way to determining beforehand if the images is a default image from gravatar or a custom one set by the user.

I've noticed that the default image i don't want ends up redirecting to a different URL. Is there a way to have Picasso download images, but notify me if the url i provide it with redirects it to another site so that i can handle default images on my own?