Description:
------------
---
From manual page: http://www.php.net/datetime.add
---
using the script in the example:
  $date = new DateTime('2369-12-30');
  $date->add(new DateInterval('P1D'));
  echo $date->format('Y-m-d');
the result is '2370-01-00' (wrong), instead of '2369-12-31'

Same problem if we use:
  $dateW2 = new DateTime('2369-12-31');
  echo date_format($dateW2, 'Y-m-d');
the result is '2370-01-00' (wrong), instead of '2369-12-31'


Test script:
---------------
$date = new DateTime('2369-12-30');
$date->add(new DateInterval('P1D'));
echo $date->format('Y-m-d') . "\n";

$dateW2 = new DateTime('2369-12-31');
echo date_format($dateW2, 'Y-m-d');