/usr/lib/ruby/vendor_ruby/ is in ruby-rabl 0.11.0-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/rabl/
/usr/lib/ruby/vendor_ruby/rabl/cache_engine.rb
/usr/lib/ruby/vendor_ruby/rabl/version.rb
/usr/lib/ruby/vendor_ruby/rabl/digestor.rb
/usr/lib/ruby/vendor_ruby/rabl/partials.rb
/usr/lib/ruby/vendor_ruby/rabl/template.rb
/usr/lib/ruby/vendor_ruby/rabl/tracker.rb
/usr/lib/ruby/vendor_ruby/rabl/railtie.rb
/usr/lib/ruby/vendor_ruby/rabl/helpers.rb
/usr/lib/ruby/vendor_ruby/rabl/builder.rb
/usr/lib/ruby/vendor_ruby/rabl/configuration.rb
/usr/lib/ruby/vendor_ruby/rabl/engine.rb
/usr/lib/ruby/vendor_ruby/rabl/renderer.rb
/usr/lib/ruby/vendor_ruby/rabl.rb