/usr/lib/ruby/vendor_ruby/abstract_controller/ is in ruby-actionpack 2:4.2.6-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/abstract_controller/asset_paths.rb
/usr/lib/ruby/vendor_ruby/abstract_controller/base.rb
/usr/lib/ruby/vendor_ruby/abstract_controller/callbacks.rb
/usr/lib/ruby/vendor_ruby/abstract_controller/collector.rb
/usr/lib/ruby/vendor_ruby/abstract_controller/helpers.rb
/usr/lib/ruby/vendor_ruby/abstract_controller/logger.rb
/usr/lib/ruby/vendor_ruby/abstract_controller/railties/
/usr/lib/ruby/vendor_ruby/abstract_controller/railties/routes_helpers.rb
/usr/lib/ruby/vendor_ruby/abstract_controller/rendering.rb
/usr/lib/ruby/vendor_ruby/abstract_controller/translation.rb
/usr/lib/ruby/vendor_ruby/abstract_controller/url_for.rb