// suffice here, but that requires deviating from the infrastructure
	// provided by `run`.
	gitDir := chomp(run(goroot, 0, "git", "rev-parse", "--git-dir"))
	if !filepath.IsAbs(gitDir) {
		gitDir = filepath.Join(goroot, gitDir)
	}
	return isdir(gitDir)
}

/*
 * Initial tree setup.
 */

// The old tools that no longer live in $GOBIN or $GOROOT/bin.