/usr/lib/ruby/ is in ruby-delayed-job-active-record 4.0.3-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/
/usr/lib/ruby/vendor_ruby/generators/
/usr/lib/ruby/vendor_ruby/generators/delayed_job/
/usr/lib/ruby/vendor_ruby/generators/delayed_job/active_record_generator.rb
/usr/lib/ruby/vendor_ruby/generators/delayed_job/upgrade_generator.rb
/usr/lib/ruby/vendor_ruby/generators/delayed_job/templates/
/usr/lib/ruby/vendor_ruby/generators/delayed_job/templates/migration.rb
/usr/lib/ruby/vendor_ruby/generators/delayed_job/templates/upgrade_migration.rb
/usr/lib/ruby/vendor_ruby/generators/delayed_job/next_migration_version.rb
/usr/lib/ruby/vendor_ruby/delayed_job_active_record.rb
/usr/lib/ruby/vendor_ruby/delayed/
/usr/lib/ruby/vendor_ruby/delayed/backend/
/usr/lib/ruby/vendor_ruby/delayed/backend/active_record.rb