Description:
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Adding a year to a DateTime produces different results for different timezone.

IMO, the test script below should produce two identical date/time strings.  However, the actual results are an hour apart.

Expected:
03/12/2016 12:00 am
03/12/2016 12:00 pm

Actual:
03/12/2016 12:00 am
03/11/2016 11:00 pm

Thank you!

Test script:
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<?php

$ct = new \DateTimeZone('America/Chicago');
$utc = new \DateTimeZone('UTC');
$oneYear = new \DateInterval('P1Y');

$date1 = \DateTime::createFromFormat('Y-m-d H:i:s', '2015-03-12 00:00:00', $ct);
$date1->add($oneYear);
echo "\n". $date1->format("m/d/Y h:i a");

$date2 = \DateTime::createFromFormat('Y-m-d H:i:s', '2015-03-12 00:00:00', $ct);
$date2->setTimezone($utc);
$date2->add($oneYear);
$date2->setTimezone($ct);
echo "\n". $date2->format("m/d/Y h:i a");



Expected result:
----------------
Expected:
03/12/2016 12:00 am
03/12/2016 12:00 pm

Actual result:
--------------
Actual:
03/12/2016 12:00 am
03/11/2016 11:00 pm