/usr/ is in ruby-sanitize 2.1.0-2+deb9u1.
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/usr/lib/ruby/vendor_ruby/sanitize/
/usr/lib/ruby/vendor_ruby/sanitize/config/
/usr/lib/ruby/vendor_ruby/sanitize/config/basic.rb
/usr/lib/ruby/vendor_ruby/sanitize/config/relaxed.rb
/usr/lib/ruby/vendor_ruby/sanitize/config/restricted.rb
/usr/lib/ruby/vendor_ruby/sanitize/config.rb
/usr/lib/ruby/vendor_ruby/sanitize/transformers/
/usr/lib/ruby/vendor_ruby/sanitize/transformers/clean_cdata.rb
/usr/lib/ruby/vendor_ruby/sanitize/transformers/clean_comment.rb
/usr/lib/ruby/vendor_ruby/sanitize/transformers/clean_element.rb
/usr/lib/ruby/vendor_ruby/sanitize/version.rb
/usr/lib/ruby/vendor_ruby/sanitize.rb
/usr/share/doc/ruby-sanitize/
/usr/share/doc/ruby-sanitize/README.md.gz
/usr/share/doc/ruby-sanitize/changelog.Debian.gz
/usr/share/doc/ruby-sanitize/changelog.gz
/usr/share/doc/ruby-sanitize/copyright
/usr/share/rubygems-integration/
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/usr/share/rubygems-integration/all/specifications/
/usr/share/rubygems-integration/all/specifications/sanitize-2.1.0.gemspec