We have a Zend Framework 2 app that's failing on our test environment at Zend\ServiceManager\ServiceManager->createFromFactory() with "an invalid factory was registered for this instance type" exception. We've pinpointed this down to a class_exists() call that's failing on test, passing in development.
The code is the same as development. Both environments are running Ubuntu 12.04 and slightly different versions of PHP 5.3.10. We've tried disabling xcache but this doesn't help.
What would cause these very similar environments to generate different result for class_exists()? The rest of the app is working fine, just this call for one particular factory is failing. Namespaces and configurations have been double checked.
