Is HTTP digest authentication still supported in Rails 3?

I tried the following code in Rails 2.3.5, it works.

class Admin::BaseController < ApplicationController
  before_filter :authenticate
  USERS = { "lifo" => "world" }
  def authenticate
    authenticate_or_request_with_http_digest("Application") do |name|
      USERS[name]
    end
  end
end

Now, the same thing in Rails 3.0.0.beta) returns an error:

can't convert nil into String

Am I missing something or is this a bug in Rails 3? HTTP basic authentication works fine.