User streams don't include list notifications for private lists
Steps to reproduce:
* Find a random user (I used @twitter)
* Click add to list
* Click new list
* Give it a name (I used "test"), make it private
* Click create list (web interface will now show the newly created list with the user in it)
REST API does show the new user, but the stream does not. When doing the exact same steps with a public list, it did work.
This is not related to the actual creation: when adding/removing from a list that already exists, the same issue occurs.