Segfault with spl_autoload

I am experiencing a segfault with spl_autoload in the PHP_5_1 branch
with the upcoming PHPUnit 2.3.0.

The nature of PHPUnit's complexity makes it almost impossible for me to
come up with a simple, reproducing script (I already invested hours into
this, to no avail so far).

It is weird that the segfault only occurs in one out of two common
code paths of PHPUnit's TextUI test runner.

Furthermore, small code changes (see below) seem to make the problem
go away:

Segfault:

function PHPUnit2_Util_Classloader($className) {
    print "Loading $className.\n";

    if (strpos($className, 'PHPUnit2_') !== FALSE) {
        @include(str_replace('_', '/', $className) . '.php');
    }
}

spl_autoload_register('PHPUnit2_Util_Classloader');

Segfault:

function PHPUnit2_Util_Classloader($className) {
    $bt = `debug_backtrace()`;
    print "Loading $className.\n";

    if (strpos($className, 'PHPUnit2_') !== FALSE) {
        @include(str_replace('_', '/', $className) . '.php');
    }
}

spl_autoload_register('PHPUnit2_Util_Classloader');

No Segfault:

function PHPUnit2_Util_Classloader($className) {
    $bt = `debug_backtrace()`;
    print_r($bt[1]);
    print "Loading $className.\n";

    if (strpos($className, 'PHPUnit2_') !== FALSE) {
        @include(str_replace('_', '/', $className) . '.php');
    }
}

spl_autoload_register('PHPUnit2_Util_Classloader');

Below are the links to the results of GDB and Valgrind. Interestingly,
when run through GDB it segfaults, when run through Valgrind it does
not segfault.

GDB: http://www.sebastian-bergmann.de/stuff/phpunit2-gdb.txt
Valgrind: http://www.sebastian-bergmann.de/stuff/phpunit2-valgrind.txt

--
Sebastian Bergmann http://www.sebastian-bergmann.de/
GnuPG Key: 0xB85B5D69 / 27A7 2B14 09E4 98CD 6277 0E5B 6867 C514 B85B 5D69