/usr/lib/ruby/vendor_ruby/action_dispatch/middleware/templates/rescues/ is in ruby-actionpack 2:4.2.6-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/action_dispatch/middleware/templates/rescues/_request_and_response.html.erb
/usr/lib/ruby/vendor_ruby/action_dispatch/middleware/templates/rescues/_request_and_response.text.erb
/usr/lib/ruby/vendor_ruby/action_dispatch/middleware/templates/rescues/_source.erb
/usr/lib/ruby/vendor_ruby/action_dispatch/middleware/templates/rescues/_trace.html.erb
/usr/lib/ruby/vendor_ruby/action_dispatch/middleware/templates/rescues/_trace.text.erb
/usr/lib/ruby/vendor_ruby/action_dispatch/middleware/templates/rescues/diagnostics.html.erb
/usr/lib/ruby/vendor_ruby/action_dispatch/middleware/templates/rescues/diagnostics.text.erb
/usr/lib/ruby/vendor_ruby/action_dispatch/middleware/templates/rescues/layout.erb
/usr/lib/ruby/vendor_ruby/action_dispatch/middleware/templates/rescues/missing_template.html.erb
/usr/lib/ruby/vendor_ruby/action_dispatch/middleware/templates/rescues/missing_template.text.erb
/usr/lib/ruby/vendor_ruby/action_dispatch/middleware/templates/rescues/routing_error.html.erb
/usr/lib/ruby/vendor_ruby/action_dispatch/middleware/templates/rescues/routing_error.text.erb
/usr/lib/ruby/vendor_ruby/action_dispatch/middleware/templates/rescues/template_error.html.erb
/usr/lib/ruby/vendor_ruby/action_dispatch/middleware/templates/rescues/template_error.text.erb
/usr/lib/ruby/vendor_ruby/action_dispatch/middleware/templates/rescues/unknown_action.html.erb
/usr/lib/ruby/vendor_ruby/action_dispatch/middleware/templates/rescues/unknown_action.text.erb