message: Show verify button when we have a device to verify
  rather than when we don't
diff: @@ -234,7 +234,7 @@ export default class KeyBackupPanel extends React.PureComponent {
  }
  let verifyButton;
  - if (!sig.device || !sig.device.isVerified()) {
  + if (sig.device && !sig.device.isVerified()) {
  verifyButton = <div><br /><AccessibleButton className="mx_UserSettings_button"
  onClick={this._verifyDevice} data-sigindex={i}>
  { _t("Verify...") }
  