Always symlink/copy local node_modules into .meteor/local/build.

Part of #6500.

tools/isobuild/bundler.js

@@ -1615,7 +1615,8 @@ class JsImage {
       // We need to find the actual file system location for the node modules
       // this JS Image uses, so that we can add it to nodeModulesDirectories
       var modulesPhysicalLocation;
-      if (! options.includeNodeModules ||
+      if (nmd.local ||
+          ! options.includeNodeModules ||
           options.includeNodeModules === 'symlink') {
         modulesPhysicalLocation = nmd.getPreferredBundlePath("bundle");
       } else if (options.includeNodeModules === 'reference-directly') {