On the 3rd of July a new version of jquery-ui-rails was released. Since then new installs get 5.0.0, which doesn't work with foreman:

Sprockets::FileNotFound in Users#login

Showing /tmp/foreman/app/views/layouts/base.html.erb where line #15 raised:

couldn't find file 'jquery.ui.autocomplete'
  (in /tmp/foreman/app/assets/stylesheets/application.scss:2)