问题1：

Auto packing the repository in background for optimum performance.

See "git help gc" for manual housekeeping.

error: inflate: data stream error (unknown compression method)

error: unable to unpack a8cc8b2de688c71c94916e6591a8bd77addb371d header

error: inflate: data stream error (unknown compression method)

fatal: loose object a8cc8b2de688c71c94916e6591a8bd77addb371d (stored in .git/objects/a8/cc8b2de688c71c94916e6591a8bd77addb371d) is corrupt

error: failed to run reflog

Already up-to-date.

解决方案： 
删掉 .git/objects/a8/cc8b2de688c71c94916e6591a8bd77addb371d 文件, 重新 git pull 一下。

实在不行，重新下载服务端代码，然后把之前更改的代码放到新下载的项目

问题2：

Git – fatal: Unable to create ‘/.git/index.lock’: File exists.

fatal: Unable to create ‘/path/my_proj/.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.

解决方案： 
可以试着删除 index.lock 
rm -f ./.git/index.lock