/usr/lib/ruby/vendor_ruby/ is in ruby-redcloth 4.2.9-3.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/case_sensitive_require/
/usr/lib/ruby/vendor_ruby/case_sensitive_require/RedCloth.rb
/usr/lib/ruby/vendor_ruby/1.9.1/
/usr/lib/ruby/vendor_ruby/1.9.1/x86_64-linux/
/usr/lib/ruby/vendor_ruby/1.9.1/x86_64-linux/redcloth_scan.so
/usr/lib/ruby/vendor_ruby/tasks/
/usr/lib/ruby/vendor_ruby/tasks/pureruby.rake
/usr/lib/ruby/vendor_ruby/redcloth.rb
/usr/lib/ruby/vendor_ruby/redcloth/
/usr/lib/ruby/vendor_ruby/redcloth/textile_doc.rb
/usr/lib/ruby/vendor_ruby/redcloth/formatters/
/usr/lib/ruby/vendor_ruby/redcloth/formatters/latex_entities.yml
/usr/lib/ruby/vendor_ruby/redcloth/formatters/base.rb
/usr/lib/ruby/vendor_ruby/redcloth/formatters/html.rb
/usr/lib/ruby/vendor_ruby/redcloth/formatters/latex.rb
/usr/lib/ruby/vendor_ruby/redcloth/erb_extension.rb
/usr/lib/ruby/vendor_ruby/redcloth/version.rb