View file core/libs/s3/vendor/composer/installers/src/Composer/Installers/LithiumInstaller.php

<?php
namespace Composer\Installers;

class LithiumInstaller extends BaseInstaller
{
    protected $locations = array(
        'library' => 'libraries/{$name}/',
        'source'  => 'libraries/_source/{$name}/',
    );
}