From what I can tell, these places would have to change:
railties/lib/rails/generators/erb/mailer/templates/layout.html.erb.tt:2:<html>
railties/lib/rails/generators/rails/app/templates/app/views/layouts/application.html.erb.tt:2:<html>
railties/lib/rails/generators/rails/app/templates/app/views/layouts/mailer.html.erb.tt:2:<html>
railties/lib/rails/generators/rails/app/templates/public/404.html:2:<html>
railties/lib/rails/generators/rails/app/templates/public/422.html:2:<html>
railties/lib/rails/generators/rails/app/templates/public/500.html:2:<html>
railties/lib/rails/generators/rails/plugin/templates/app/views/layouts/%namespaced_name%/application.html.erb.tt:2:<html>
railties/lib/rails/templates/layouts/application.html.erb:2:<html lang="en">
railties/lib/rails/templates/rails/mailers/email.html.erb:2:<html><head>
railties/lib/rails/templates/rails/welcome/index.html.erb:2:<html>
It seems other parts are already using lang=“en” default. So I wonder if we just use that, because i18n is optional right? I guess we could detect it and use I18n.default_locale if it’s available…
