OmniAuth open_id logout not working as expected

Question

I'm using 'omniauth' and 'omniauth-openid' gem for my rails applications. Log in works as expected, it creates a new session after call back from openId provider. The problem is with logout.

In my controller, i'm having this code to destroy session.

def destroy
  session.delete(:user)
  @current_user = nil
  redirect_to root_path
end

My logout route is calling this action. When i logout, i see that the user on the session is set to nil as expected. Now when i enter the homepage URL, my helper method is checking to see if the user is already logged in, and it returns false at this point and redirects to the '/auth/open_id?origin=request.url' as expected. The problem starts here, Now before i even provide the credentials, the provider POSTs callback and creates new session with the same user. What am i doing wrong?