code: private function mockLocalRepositories(RepositoryManager $rm)
      {
          $packages = array();
          foreach ($rm->getLocalRepository()->getPackages() as $package) {
              $packages[(string) $package] = clone $package;
          }
          foreach ($packages as $key => $package) {
              if ($package instanceof AliasPackage) {
                  $alias = (string) $package->getAliasOf();
                  $packages[$key] = new AliasPackage($packages[$alias], $package->getVersion(), $package->getPrettyVersion());
              }
          }
          $rm->setLocalRepository(
              new InstalledArrayRepository($packages)
          );
      }
docs: Replace local repositories with InstalledArrayRepository instances
  
  This is to prevent any accidental modification of the existing repos on disk
  
  @param RepositoryManager $rm