http://pkg.phpcomposer.com/repo/packagist/ 到底靠不靠谱啊？

这个镜像怎么一会能用，一会又不能的啊？
今天又出了下面的错误：
$composer require laravel/homestead

[Composer\Downloader\TransportException]

The "http://pkg.phpcomposer.com/rep ... ot%3B file could not be downloaded (HTTP/1.1 504 Gateway Time-out)

require [--dev] [--prefer-source] [--prefer-dist] [--no-progress] [--no-update] [--update-no-dev] [--update-with-dependencies] [--ignore-platform-reqs] [--sort-packages] [packages1] ... [packagesN]