When you preview coreos provision template, it renders an error: "There was an error during rendering, return to the Code tab to edit the template."

Looking at the logs reveals:

2018-03-26T09:59:36 7c9264d0 [app] [W] Error rendering the CoreOS provision template
 | Safemode::NoMethodError: undefined method '#release' for Operatingsystem::Jail (Redhat)
 | /usr/local/rvm/gems/ruby-2.4.1@foreman/gems/safemode-1.3.4/lib/safemode/jail.rb:22:in `method_missing'
 | CoreOS provision:58:in `bind'
 | /usr/local/rvm/gems/ruby-2.4.1@foreman/gems/safemode-1.3.4/lib/safemode.rb:51:in `eval'
 | /usr/local/rvm/gems/ruby-2.4.1@foreman/gems/safemode-1.3.4/lib/safemode.rb:51:in `eval'
 | /home/shim/Documents/foreman/foreman/lib/foreman/renderer.rb:84:in `render_safe'
 | /home/shim/Documents/foreman/foreman/lib/foreman/renderer.rb:202:in `unattended_render'
 | /home/shim/Documents/foreman/foreman/app/controllers/templates_controller.rb:115:in `safe_render'
 | /home/shim/Documents/foreman/foreman/app/controllers/templates_controller.rb:96:in `preview'
 | /usr/local/rvm/gems/ruby-2.4.1@foreman/gems/actionpack-5.1.4/lib/action_controller/metal/basic_implicit_render.rb:4:in `send_action'
 | /usr/local/rvm/gems/ruby-2.4.1@foreman/gems/actionpack-5.1.4/lib/abstract_controller/base.rb:186:in `process_action'
 | /usr/local/rvm/gems/ruby-2.4.1@foreman/gems/actionpack-5.1.4/lib/action_controller/metal/rendering.rb:30:in `process_action'
 | /usr/local/rvm/gems/ruby-2.4.1@foreman/gems/actionpack-5.1.4/lib/abstract_controller/callbacks.rb:20:in `block in process_action'