Fix Courses_CourseModel::findParentOfRequest() to not bomb out when given an empty array.

application/modules/courses/models/CourseModel.php

@@ -232,6 +232,9 @@ class Courses_CourseModel extends Unl_Model
 		$db = Zend_Registry::get('db');
 
 		if (Unl_Util::isArray($request)) {
+			if (count($request) == 0) {
+				return new Unl_Model_Collection(__CLASS__);
+			}
 			$requestId = array();
 			foreach ($request as $aRequest) {
 				$requestId[] = $aRequest->getId();