code: func goFromGit(repo, tag string) llb.StateOption {
  	src := llb.Image("docker.io/library/alpine:latest").
  		Run(llb.Shlex("apk add --no-cache git")).
  		Run(llb.Shlexf("git clone https://%[1]s.git /go/src/%[1]s", repo)).
  		Dirf("/go/src/%s", repo).
  		Run(llb.Shlexf("git checkout -q %s", tag)).Root()
  	return func(s llb.State) llb.State {
  		return s.With(copyFrom(src, "/go", "/")).Reset(s).Dir(src.GetDir())
  	}
  }
docs: // goFromGit is a helper for cloning a git repo, checking out a tag and copying
  // source directory into