Description:
------------
https://3v4l.org/7CmJA

please fix. ktnxbai :P

Test script:
---------------
<?php

date_default_timezone_set('UTC');

$date = new DateTime('2015-01-01T12:00:00-05:00');
$timezone = $date->getTimezone();
echo $date->format('H:i'); // 12:00
echo "\n";

$date->setTimezone(new DateTimeZone('UTC'));
echo $date->format('H:i'); // 17:00
echo "\n";

$date->setTimezone($timezone);
echo $date->format('H:i'); // 12:00
echo "\n";

$date->setTimezone(new DateTimeZone('UTC'));
echo $date->format('H:i'); // 12:00 ???
echo "\n";