/usr/lib/ruby/vendor_ruby/ is in ruby-rabl-rails 0.4.1-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/rabl-rails/
/usr/lib/ruby/vendor_ruby/rabl-rails.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/compiler.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/configuration.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/handler.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/helpers.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/library.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/nodes/
/usr/lib/ruby/vendor_ruby/rabl-rails/nodes.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/nodes/attribute.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/nodes/child.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/nodes/code.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/nodes/condition.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/nodes/glue.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/nodes/node.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/railtie.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/renderer.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/renderers/
/usr/lib/ruby/vendor_ruby/rabl-rails/renderers/hash.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/renderers/json.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/renderers/plist.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/renderers/xml.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/responder.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/template.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/version.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/visitors/
/usr/lib/ruby/vendor_ruby/rabl-rails/visitors.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/visitors/to_hash.rb
/usr/lib/ruby/vendor_ruby/rabl-rails/visitors/visitor.rb
/usr/lib/ruby/vendor_ruby/tasks/
/usr/lib/ruby/vendor_ruby/tasks/rabl-rails.rake