Test script:

<?php

print "xdebug is " . (xdebug_is_enabled() ? "on" : "off") . "\n";

class Food {
public function destruct() {
echo "destruct called\n";
}
}

$f = new Food();
echo "forcing fatal error:\n";
Abc::def();

?>

==
Xdebug on, problem happens:

% /tmp/php-5.2.6/bin/php test.php
xdebug is on
forcing fatal error:

Fatal error: Class 'Abc' not found in /private/tmp/xdebug-destructor-test/test.php on line 13

Call Stack:
0.0003 52312 1. {main}() /private/tmp/xdebug-destructor-test/test.php:0

__destruct called

==
Xdebug off, no problem:

% /tmp/php-5.2.6/bin/php -d xdebug.default_enable=0 test.php
xdebug is off
forcing fatal error:

Fatal error: Class 'Abc' not found in /private/tmp/xdebug-destructor-test/test.php on line 13