Authenticate metadata box urls

lib/vagrant/action/builtin/box_add.rb

@@ -253,7 +253,7 @@ module Vagrant
           end
 
           provider_url = metadata_provider.url
-          if url != authenticated_url
+          if provider_url != authenticated_url
             # Authenticate the provider URL since we're using auth
             hook_env    = env[:hook].call(:authenticate_box_url, box_urls: [provider_url])
             authed_urls = hook_env[:box_urls]