Description:
------------
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:

Reproduce code:
---------------
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');

Actual result:
--------------
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