Ignore xml comments in scenario files

mentoring/light_children.py

@@ -99,6 +99,8 @@ class LightChildrenMixin(XBlockWithChildrenFragmentsMixin):
 
     @classmethod
     def add_node_as_child(cls, block, xml_child, child_id):
+        if xml_child.tag is etree.Comment:
+                return
         # Instantiate child
         child_class = cls.get_class_by_element(xml_child.tag)
         child = child_class(block)

tests/integration/xml/mcq_with_comments_1.xml

@@ -12,6 +12,8 @@
             <tip require="elegance" width ="600" height = "800">This is something everyone has to like about this MRQ</tip>
             <tip require="beauty" width ="400" height = "600">This is something everyone has to like about beauty</tip>
             <tip reject="bugs" width = "100" height = "200">Nah, there isn\'t any!</tip>
+
+            <!--<message type="on-submit">Thank you for answering!</message> -->
         </mrq>
 
         <message type="completed">