Incorrectly handles daylight savings time

In the summer, articles posted shortly before midnight will often show up on the page for the following day:

Posted by GeneBreshears on Thu 7 Jun 2001 - 16:34
[...]
Posted by Rigel on Thu 6 Jun 2002 - 23:58

The code that determines the offset includes the following line:
$year_ago = mktime(0, 0, 0, $month, $day, $year - $offset);

mktime has another parameter telling it whether to correct for DST or not. If it is not set, then it will default to -1 andtry to detect whether it should apply DST. This was deprecated in PHP 5.1.0 but is apparently still working.

Adding the parameter 0 at the end appears to fix this, e.g.:
$year_ago = mktime(0, 0, 0, $month, $day, $year - $offset, 0);