Comment 0 for bug 1467253

I haven't test it yet but it is possible that the panel label and the today_button will show 'undef' as text.

 public string format (string format) {
  if (current_time == null)
   return "undef";

  return current_time.format (format);
 }

in the following links you can see this is not catched.
This is not a text you want to show the user

http://bazaar.launchpad.net/~wingpanel-devs/wingpanel-indicator-datetime/trunk/view/head:/src/Widgets/PanelLabel.vala#L26
http://bazaar.launchpad.net/~wingpanel-devs/wingpanel-indicator-datetime/trunk/view/head:/src/Indicator.vala#L90