/usr/lib/ is in ruby-html-pipeline 1.11.0-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/
/usr/lib/ruby/vendor_ruby/
/usr/lib/ruby/vendor_ruby/html/
/usr/lib/ruby/vendor_ruby/html/pipeline.rb
/usr/lib/ruby/vendor_ruby/html/pipeline/
/usr/lib/ruby/vendor_ruby/html/pipeline/version.rb
/usr/lib/ruby/vendor_ruby/html/pipeline/@mention_filter.rb
/usr/lib/ruby/vendor_ruby/html/pipeline/toc_filter.rb
/usr/lib/ruby/vendor_ruby/html/pipeline/camo_filter.rb
/usr/lib/ruby/vendor_ruby/html/pipeline/absolute_source_filter.rb
/usr/lib/ruby/vendor_ruby/html/pipeline/sanitization_filter.rb
/usr/lib/ruby/vendor_ruby/html/pipeline/image_max_width_filter.rb
/usr/lib/ruby/vendor_ruby/html/pipeline/textile_filter.rb
/usr/lib/ruby/vendor_ruby/html/pipeline/plain_text_input_filter.rb
/usr/lib/ruby/vendor_ruby/html/pipeline/filter.rb
/usr/lib/ruby/vendor_ruby/html/pipeline/https_filter.rb
/usr/lib/ruby/vendor_ruby/html/pipeline/autolink_filter.rb
/usr/lib/ruby/vendor_ruby/html/pipeline/markdown_filter.rb
/usr/lib/ruby/vendor_ruby/html/pipeline/syntax_highlight_filter.rb
/usr/lib/ruby/vendor_ruby/html/pipeline/email_reply_filter.rb
/usr/lib/ruby/vendor_ruby/html/pipeline/body_content.rb
/usr/lib/ruby/vendor_ruby/html/pipeline/emoji_filter.rb
/usr/lib/ruby/vendor_ruby/html/pipeline/text_filter.rb