解决方案
xcrun git config --global user.email you@yourdomain.com
xcrun git config --global user.name "Your Name Here"
参考:http://pinkstone.co.uk/how-to-fix-couldnt-communicate-with-a-helper-application-in-xcode-7/
"Couldn't communicate with a helper application" in Xcode 7
原文：http://www.cnblogs.com/lovelydark/p/5400289.html