Dev and edge application and plugins need to include i18n master

railties/lib/rails/generators/app_base.rb

@@ -206,10 +206,11 @@ def rails_gemfile_entry
           [GemfileEntry.path('rails', Rails::Generators::RAILS_DEV_PATH),
            GemfileEntry.github('arel', 'rails/arel'),
            GemfileEntry.github('rack', 'rack/rack')]
+           GemfileEntry.github('i18n', 'svenfuchs/i18n')]
         elsif options.edge?
           [GemfileEntry.github('rails', 'rails/rails'),
            GemfileEntry.github('arel', 'rails/arel'),
-           GemfileEntry.github('rack', 'rack/rack')]
+           GemfileEntry.github('i18n', 'svenfuchs/i18n')]
         else
           [GemfileEntry.version('rails',
                             Rails::VERSION::STRING,