/usr/lib/ruby/ is in ruby-rest-client 2.0.2-3.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/
/usr/lib/ruby/vendor_ruby/rest-client.rb
/usr/lib/ruby/vendor_ruby/rest_client.rb
/usr/lib/ruby/vendor_ruby/restclient/
/usr/lib/ruby/vendor_ruby/restclient/abstract_response.rb
/usr/lib/ruby/vendor_ruby/restclient/exceptions.rb
/usr/lib/ruby/vendor_ruby/restclient/params_array.rb
/usr/lib/ruby/vendor_ruby/restclient/payload.rb
/usr/lib/ruby/vendor_ruby/restclient/platform.rb
/usr/lib/ruby/vendor_ruby/restclient/raw_response.rb
/usr/lib/ruby/vendor_ruby/restclient/request.rb
/usr/lib/ruby/vendor_ruby/restclient/resource.rb
/usr/lib/ruby/vendor_ruby/restclient/response.rb
/usr/lib/ruby/vendor_ruby/restclient/utils.rb
/usr/lib/ruby/vendor_ruby/restclient/version.rb
/usr/lib/ruby/vendor_ruby/restclient/windows/
/usr/lib/ruby/vendor_ruby/restclient/windows/root_certs.rb
/usr/lib/ruby/vendor_ruby/restclient/windows.rb
/usr/lib/ruby/vendor_ruby/restclient.rb