Description:
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Russia have no summer/winter offset from 2011

Test script:
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$winter = new DateTime('2012-12-21', new DateTimeZone('Europe/Moscow'));
$summer = new DateTime('2012-04-21', new DateTimeZone('Europe/Moscow'));

$tz[winter]= ($winter->getOffset())/60/60;
$tz[summer]= ($summer->getOffset())/60/60;
$tz[diff]=$tz[summer]-$tz[winter];
echo $tz[diff];

Expected result:
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0

Actual result:
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1