zendframework/zf2 — pull request #827 by mwillbanks (2012-02-24 14:54:33+00:00)
Title: Fix Zend\Loader\AutoloaderFactory for PHP Versions 5.3.6 and under

is_subclass_of AND instanceof are broken in PHP versions 5.3.6 for checking of interfaces in some conditions.

This behavior has broken several peoples instances with errors that state:
Fatal error: Uncaught exception 'Zend\Loader\Exception\InvalidArgumentException' with message 'Autoloader class Zend\Loader\ClassMapAutoloader must implement Zend\Loader\SplAutoloader' in /homer/efi/speck/vendor/ZendFramework/library/Zend/Loader/AutoloaderFactory.php on line 107

This is simply due to the php version. I can verify that PHP 5.3.9 works and from the PHP changelog for 5.3.7:
Fixed bug #53727 (Inconsistent behavior of is_subclass_of with interfaces) (Ralph Schindler, Dmitry)

So this behavior will happen for all versions under 5.3.7.
The change:
1) Do not validate that the class is a subclass of Zend\Loader\SplAutoloader (nor an instanceof) by using a version check. - The only real way to check this is with reflection which is VERY expensive
2) Skip the test on using version compare