composer update的时候出现：
Failed to decode response: zlib_decode(): data error Retrying with degraded；
执行：
composer config -g repo.packagist composer https://packagist.phpcomposer.com
就解决了；
Failed to decode response: zlib_decode(): data error Retrying with degraded；
原文：http://www.cnblogs.com/Amos-Turing/p/6720836.html