message: fix moment-utils startOfDay, endOfDay
  The two methods in moment-utils invoke moment().startOf and
  moment().endOf which mutate the original value. The call to clone() has
  to be added in order to prevent that.
diff: @@ -40,11 +40,11 @@ export default class MomentUtils {
  }
  static startOfDay(date) {
  - return date.startOf('day');
  + return date.clone().startOf('day');
  }
  static endOfDay(date) {
  - return date.endOf('day');
  + return date.clone().endOf('day');
  }
  static format(date, formatString) {
  