错误：bad object refs/remotes/origin/HEAD
Removing target/
Fetching origin
Auto packing the repository in background for optimum performance.
See "git help gc" for manual housekeeping.
error: The last gc run reported the following. Please correct the root cause
and remove .git/gc.log.
Automatic cleanup will not be performed until the file is removed.
尝试解决但失败：
$ git gc
fatal: bad object refs/remotes/origin/HEAD
error: failed to run repack
最终解决：
$ mv .git/refs/remotes/origin/HEAD /tmp
$ git gc
Failed to connect to github.com port 443: Operation timed out
关闭VPN 试试，2020-02-20