Heads up: we've written the past 6 days of git history for
https://github.com/golang/go/issues/28899 (a big binary was checked in 6 days ago)
If you use "git sync", this doesn't affect you. (I just checked)
If you don't use git sync, you presumably know how to use git, but this will blow away your local work and get you back on the train:
$ git fetch origin master && git reset --hard FETCH_HEAD