/usr/lib/ruby/vendor_ruby/ is in ruby-email-spec 1.6.0-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/email-spec.rb
/usr/lib/ruby/vendor_ruby/email_spec/
/usr/lib/ruby/vendor_ruby/email_spec/address_converter.rb
/usr/lib/ruby/vendor_ruby/email_spec/background_processes.rb
/usr/lib/ruby/vendor_ruby/email_spec/cucumber.rb
/usr/lib/ruby/vendor_ruby/email_spec/deliveries.rb
/usr/lib/ruby/vendor_ruby/email_spec/email_viewer.rb
/usr/lib/ruby/vendor_ruby/email_spec/errors.rb
/usr/lib/ruby/vendor_ruby/email_spec/helpers.rb
/usr/lib/ruby/vendor_ruby/email_spec/mail_ext.rb
/usr/lib/ruby/vendor_ruby/email_spec/matchers.rb
/usr/lib/ruby/vendor_ruby/email_spec/test_observer.rb
/usr/lib/ruby/vendor_ruby/email_spec.rb
/usr/lib/ruby/vendor_ruby/generators/
/usr/lib/ruby/vendor_ruby/generators/email_spec/
/usr/lib/ruby/vendor_ruby/generators/email_spec/steps/
/usr/lib/ruby/vendor_ruby/generators/email_spec/steps/USAGE
/usr/lib/ruby/vendor_ruby/generators/email_spec/steps/steps_generator.rb
/usr/lib/ruby/vendor_ruby/generators/email_spec/steps/templates/
/usr/lib/ruby/vendor_ruby/generators/email_spec/steps/templates/email_steps.rb