MDL-18177 availability: Excluding group members availability info

If setting was not enabled when backing up, exclude the availability
information of group members.

availability/condition/grouping/classes/condition.php

@@ -158,6 +158,13 @@ class condition extends \core_availability\condition {
         }
     }
 
+    public function include_after_restore($restoreid, $courseid, \base_logger $logger,
+            $name, \base_task $task) {
+        // Include this condition only if we are including groups in restore, or
+        // if it's a generic 'same activity' one.
+        return !$this->groupingid || $task->get_setting_value('groups');
+    }
+
     public function update_after_restore($restoreid, $courseid, \base_logger $logger, $name) {
         global $DB;
         if (!$this->groupingid) {