报错：composer.json 的 require添加新包 需要删除composer.lock和vender 从新composer install
[RuntimeException]
Failed to execute git checkout ‘xxxx‘ -- && git reset --hard ‘xxxxx‘ --
error: unable to read sha1 file of xxxxxx (xxxx)
......
......
解决方法：
composer clear
composer install
参考：https://segmentfault.com/q/1010000018768672
composer install 出现 RuntimeException Failed to execute
原文：https://www.cnblogs.com/songyanan/p/13294282.html