Append vendor/javascript to the sprockets manifest

Author: David Heinemeier Hansson

lib/install/install.rb

@@ -16,7 +16,8 @@
 
 if (sprockets_manifest_path = Rails.root.join("app/assets/config/manifest.js")).exist?
   say "Ensure JavaScript files are in the Sprocket manifest"
-  append_to_file sprockets_manifest_path, %(//= link_tree ../../javascript .js\n)
+  append_to_file sprockets_manifest_path,
+    %(//= link_tree ../../javascript .js\n//= link_tree ../../../vendor/javascript .js\n)
 end
 
 say "Configure importmap paths in config/importmap.rb"