return "", err
	}
	return modRoot, nil
}

// cloneGOROOTDeps copies (or symlinks) the portions of GOROOT/src and
// GOROOT/pkg relevant to this test into the given directory.
// It must be run from within the testdata module.
func cloneGOROOTDeps(goroot string) error {
	// Before we clone GOROOT, figure out which packages we need to copy over.
	listArgs := []string{