/usr/lib/ruby/vendor_ruby/rails/templates/ is in ruby-railties 2:4.2.6-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/rails/templates/layouts/
/usr/lib/ruby/vendor_ruby/rails/templates/layouts/application.html.erb
/usr/lib/ruby/vendor_ruby/rails/templates/rails/
/usr/lib/ruby/vendor_ruby/rails/templates/rails/info/
/usr/lib/ruby/vendor_ruby/rails/templates/rails/info/properties.html.erb
/usr/lib/ruby/vendor_ruby/rails/templates/rails/info/routes.html.erb
/usr/lib/ruby/vendor_ruby/rails/templates/rails/mailers/
/usr/lib/ruby/vendor_ruby/rails/templates/rails/mailers/email.html.erb
/usr/lib/ruby/vendor_ruby/rails/templates/rails/mailers/index.html.erb
/usr/lib/ruby/vendor_ruby/rails/templates/rails/mailers/mailer.html.erb
/usr/lib/ruby/vendor_ruby/rails/templates/rails/welcome/
/usr/lib/ruby/vendor_ruby/rails/templates/rails/welcome/index.html.erb