it seems that easter_date doesn't use the date.timezone but the TZ environment variable, so it passing the return value of easter_date() to date() which uses the date.timezone will create wrong result.

Author: Tyrael

ext/calendar/tests/easter_date.phpt

@@ -6,6 +6,7 @@ date.timezone=UTC
 <?php include 'skipif.inc'; ?>
 --FILE--
 <?php
+putenv('TZ=UTC');
 echo date("Y-m-d", easter_date(2000))."\n";       
 echo date("Y-m-d", easter_date(2001))."\n";      
 echo date("Y-m-d", easter_date(2002))."\n";