Cocospod Error "Pull is not possible because you have unmerged files"

今天项目中用到一个第三方库，运行工程，发现缺少 "DTTableViewCell.h"，从项目目录一检查，发现其目录下有个 Podfile 文件，然后打开其文件，发现里边又用到一个第三方库，于是乎，安装cocospod

$ sudo gem install cocoapods
$ pod install

结果控制台显示如下：

Pull is not possible because you have unmerged files.

Please, fix them up in the work tree, and then use `'git add/rm <file>'`

as appropriate to mark resolution, or use `'git commit -a'`

感觉很奇怪，因为我是刚从github上pull下来的，根本没有进行本地修改，网上进行求助，发现了解决方法:

$ pod repo remove master
$ pod setup

详细地址：http://stackoverflow.com/questions/21534309/cocoapods-error-pull-is-not-possible-because-you-have-unmerged-files