CallbackHandler throws warning if WeakRef-extension not installed

[alexgit2k]

library/Zend/Stdlib/CallbackHandler.php lines 103-107:

    // If pecl/weakref is not installed, simply store the callback and return
    if (!class_exists('WeakRef')) {
        $this->callback = $callback;
        return;
    }

This throws a Warning if the WeakRef-extension is not installed:
include_once(WeakRef.php): failed to open stream: File not found

It would be better to catch the error in the same way as a few lines above in CallbackHandler.php:

    set_error_handler(array($this, 'errorHandler'), E_WARNING);
    $callable = class_exists('WeakRef');
    restore_error_handler();
    if (!$callable || $this->error) {
        $this->callback = $callback;
        return;
    }