module ActionController::Rescue

def process_action(*)
  super
rescue Exception => exception
  request.env["action_dispatch.show_detailed_exceptions"] ||= show_detailed_exceptions?
  rescue_with_handler(exception) || raise
end

requests in production still show the detailed exception pages.
+false+, but someone may set it to request.local? so local
+consider_all_requests_local+ is +false+. By default, it returns
exceptions must be shown. This method is only called when
Override this method if you want to customize when detailed

def show_detailed_exceptions?
  false
end