// and from parent directories all the way up to the root of subdir.
// go.mod and go.sum files are needed for the go tool modules queries,
// and the testdata directories for tests.  It is common for tests to
// reach out into testdata from parent packages.
func adbCopyTree(deviceCwd, subdir string) error {
	dir := ""
	for {
		for _, name := range []string{"testdata", "go.mod", "go.sum"} {
			hostPath := filepath.Join(dir, name)