有时候在提交的时候，中间提交出错，导致有文件被lock，所以会报下面的错误：
fatal: Unable to create ‘/msg/.git/index.lock’: File exists.
If no other git process is currently running, this probably means a git process crashed in this repository earlier. Make sure no other git process is running and remove the file manually to continue.
出现这种情况可以用以下解决办法：
试着删除 index.lock
1、命令行代码 rm -f ./msg/.git/index.lock
2、直接去文件系统进行删除该lock文件