Description:
------------
When you try an absolute diff between '2016-03-31' and '2016-03-01', you'll have an extra day field.

Test script:
---------------
$date1 = new \DateTime('2016-03-01');
$date2 = new \DateTime('2016-03-31');

$diff = date_diff($date1, $date2, true);

var_dump($diff);


Expected result:
----------------
class DateInterval#2 (15) {
  public $y =>
  int(0)
  public $m =>
  int(1)
  public $d =>
  int(0)
  public $h =>
  int(0)
  public $i =>
  int(0)
  public $s =>
  int(0)
  public $weekday =>
  int(0)
  public $weekday_behavior =>
  int(0)
  public $first_last_day_of =>
  int(0)
  public $invert =>
  int(0)
  public $days =>
  int(30)
  public $special_type =>
  int(0)
  public $special_amount =>
  int(0)
  public $have_weekday_relative =>
  int(0)
  public $have_special_relative =>
  int(0)
}


Actual result:
--------------
class DateInterval#2 (15) {
  public $y =>
  int(0)
  public $m =>
  int(1)
  public $d =>
  int(1)
  public $h =>
  int(0)
  public $i =>
  int(0)
  public $s =>
  int(0)
  public $weekday =>
  int(0)
  public $weekday_behavior =>
  int(0)
  public $first_last_day_of =>
  int(0)
  public $invert =>
  int(0)
  public $days =>
  int(30)
  public $special_type =>
  int(0)
  public $special_amount =>
  int(0)
  public $have_weekday_relative =>
  int(0)
  public $have_special_relative =>
  int(0)
}