anchor.diff:          } else {
             // pubspec was added in a sub-folder, extract a new context
             if (_isPubspec(path) &&
  -              info.isRoot &&
  +              info.isTopLevel &&
                 !info.isPathToPackageDescription(path)) {
               _extractContext(info, resource);
               return;
  
positive.code:         // If package spec info is removed, check to see if we can merge contexts.
          // Note that it's important to verify that there is NEITHER a .packages nor a
          // lingering pubspec.yaml before merging.
          if (!info.isRoot) {
            if (ENABLE_PACKAGESPEC_SUPPORT) {
              String directoryPath = pathContext.dirname(path);
  
  
negative.code:    * Virtual [ContextInfo] which acts as the ancestor of all other
     * [ContextInfo]s.
     */
    final ContextInfo _rootInfo = new ContextInfo._root();
  
    ContextManagerImpl(this.resourceProvider, this.packageResolverProvider,
        this._packageMapProvider, this._instrumentationService) {
  