/usr/lib/ruby/vendor_ruby/action_dispatch/http/ 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/http/cache.rb
/usr/lib/ruby/vendor_ruby/action_dispatch/http/filter_parameters.rb
/usr/lib/ruby/vendor_ruby/action_dispatch/http/filter_redirect.rb
/usr/lib/ruby/vendor_ruby/action_dispatch/http/headers.rb
/usr/lib/ruby/vendor_ruby/action_dispatch/http/mime_negotiation.rb
/usr/lib/ruby/vendor_ruby/action_dispatch/http/mime_type.rb
/usr/lib/ruby/vendor_ruby/action_dispatch/http/mime_types.rb
/usr/lib/ruby/vendor_ruby/action_dispatch/http/parameter_filter.rb
/usr/lib/ruby/vendor_ruby/action_dispatch/http/parameters.rb
/usr/lib/ruby/vendor_ruby/action_dispatch/http/rack_cache.rb
/usr/lib/ruby/vendor_ruby/action_dispatch/http/request.rb
/usr/lib/ruby/vendor_ruby/action_dispatch/http/response.rb
/usr/lib/ruby/vendor_ruby/action_dispatch/http/upload.rb
/usr/lib/ruby/vendor_ruby/action_dispatch/http/url.rb