Laravel一个package的问题，composer update出错

一个laravel html转pdf得插件
http://packalyst.com/packages/ ... l2pdf
按照英文的安装说明，在composer.json里面加入"nitmedia/wkhtml2pdf": "dev-master"执行
Composer update

会出现以下问题：

Loading composer repositories with package information
Updating dependencies (including require-dev)
- Installing nitmedia/wkhtml2pdf (dev-master 5f3c13a)
Cloning 5f3c13aab1d543a7bc68656616e7298c3e414647

[Symfony\Component\Process\Exception\ProcessTimedOutException]

The process "git clone 'git://github.com/NitMedia/wkhtml2pdf.git' '/Users/m

ac/Sites/test2/vendor/nitmedia/wkhtml2pdf' && cd '/Users/mac/Sites/test2/ve

ndor/nitmedia/wkhtml2pdf' && git remote add composer 'git://github.com/NitM

edia/wkhtml2pdf.git' && git fetch composer" exceeded the timeout of 300 sec

onds.
请大神指点这种情况应该怎么处理，确定不是时间问题，把时间300设为2000的响应时间还是不行。