Description:
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strtotime() returns invalid timestamp with DST transition at new year midnight

Test script:
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date_default_timezone_set("Europe/Vilnius");
echo date("Y-m-d H:i:s", strtotime("2002-12-31 23:59:59 +1 sec")) . "\n";
date_default_timezone_set("Asia/Baku");
echo date("Y-m-d H:i:s", strtotime("1995-12-31 23:59:59 +1 sec")) . "\n";
date_default_timezone_set("Africa/Cairo");
echo date("Y-m-d H:i:s", strtotime("2010-09-09 23:59:59 +1 sec")) . "\n"; // OK
date_default_timezone_set("Asia/Karachi");
echo date("Y-m-d H:i:s", strtotime("2009-04-14 23:59:59 +1 sec")) . "\n"; // OK

Expected result:
----------------
2003-01-01 01:00:00
1996-01-01 01:00:00
2010-09-10 01:00:00
2009-04-15 01:00:00

Actual result:
--------------
2003-01-01 00:00:00
1996-01-01 00:00:00
2010-09-10 01:00:00
2009-04-15 01:00:00