Description:
------------
Handling the transition back from DST to default time is buggy in DatePeriod.

The extra hour is not showing when iterating over a DatePeriod covering the transition back from DST to default time.


See https://gist.github.com/heiglandreas/7b7fc82471f4619f66f329a31b566112 and https://3v4l.org/2aDp3 for code-examples.



Test script:
---------------
<?php
$interval = new DateInterval('PT1H');
// DST change in Europe is on the 30. October 2016
$dateTimeStart =  new DateTimeImmutable('2016-10-30 01:30:00', new DateTimezone('Europe/Berlin'));
$dateTimeEnd   =  new DateTimeImmutable('2016-10-30 03:31:00', new DateTimezone('Europe/Berlin'));
$period = new DatePeriod($dateTimeStart, $interval, $dateTimeEnd);
foreach ($period as $date) {
    echo $date->format('c') . "\n";
}

Expected result:
----------------
2016-10-30T01:30:00+02:00
2016-10-30T02:30:00+02:00
2016-10-30T02:30:00+01:00
2016-10-30T03:30:00+01:00

Actual result:
--------------
2016-10-30T01:30:00+02:00
2016-10-30T02:30:00+01:00
2016-10-30T03:30:00+01:00