// the format is explicitly chosen.
	// This ensures nominal usage of WriteHeader (without specifying the format)
	// does not always result in the PAX format being chosen, which
	// causes a 1KiB increase to every header.
	if tw.hdr.Format == FormatUnknown {
		tw.hdr.ModTime = tw.hdr.ModTime.Round(time.Second)
		tw.hdr.AccessTime = time.Time{}
		tw.hdr.ChangeTime = time.Time{}
	}

	}
	if string(s) == goVersion {
		return nil
	}

	goroot, err := findGoroot()
	if err != nil {
		return err
	}

	// Delete the device's GOROOT, GOPATH and any leftover test data,
	// and recreate GOROOT.
	if err := adb("exec-out", "rm", "-rf", deviceRoot); err != nil {
		return err
	}

	// Build Go for Android.
	cmd = exec.Command(goTool, "install", "cmd")
	out, err = cmd.CombinedOutput()