/usr/ is in ruby-omniauth 1.3.1-1+deb9u1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/
/usr/lib/ruby/
/usr/lib/ruby/vendor_ruby/
/usr/lib/ruby/vendor_ruby/omniauth/
/usr/lib/ruby/vendor_ruby/omniauth/auth_hash.rb
/usr/lib/ruby/vendor_ruby/omniauth/builder.rb
/usr/lib/ruby/vendor_ruby/omniauth/failure_endpoint.rb
/usr/lib/ruby/vendor_ruby/omniauth/form.css
/usr/lib/ruby/vendor_ruby/omniauth/form.rb
/usr/lib/ruby/vendor_ruby/omniauth/strategies/
/usr/lib/ruby/vendor_ruby/omniauth/strategies/developer.rb
/usr/lib/ruby/vendor_ruby/omniauth/strategy.rb
/usr/lib/ruby/vendor_ruby/omniauth/test/
/usr/lib/ruby/vendor_ruby/omniauth/test/phony_session.rb
/usr/lib/ruby/vendor_ruby/omniauth/test/strategy_macros.rb
/usr/lib/ruby/vendor_ruby/omniauth/test/strategy_test_case.rb
/usr/lib/ruby/vendor_ruby/omniauth/test.rb
/usr/lib/ruby/vendor_ruby/omniauth/version.rb
/usr/lib/ruby/vendor_ruby/omniauth.rb
/usr/share/
/usr/share/doc/
/usr/share/doc/ruby-omniauth/
/usr/share/doc/ruby-omniauth/README.md.gz
/usr/share/doc/ruby-omniauth/changelog.Debian.gz
/usr/share/doc/ruby-omniauth/copyright
/usr/share/rubygems-integration/
/usr/share/rubygems-integration/all/
/usr/share/rubygems-integration/all/specifications/
/usr/share/rubygems-integration/all/specifications/omniauth-1.3.1.gemspec