fix: Don't add x-is-pointer-node attribute to Capa problem XML on paste [FC-0062]

cms/djangoapps/contentstore/helpers.py

@@ -7,6 +7,7 @@
 import urllib
 from lxml import etree
 from mimetypes import guess_type
+import re
 
 from attrs import frozen, Factory
 from django.conf import settings
@@ -447,6 +448,10 @@ def _import_xml_node_to_parent(
         temp_xblock = xblock_class.parse_xml(node_without_children, runtime, keys)
         child_nodes = list(node)
 
+    if issubclass(xblock_class, XmlMixin) and "x-is-pointer-node" in getattr(temp_xblock, "data", ""):
+        # Undo the "pointer node" hack if needed (e.g. for capa problems)
+        temp_xblock.data = re.sub(r'([^>]+) x-is-pointer-node="no"', r'\1', temp_xblock.data, count=1)
+
     # Restore the original id_generator
     runtime.id_generator = original_id_generator
 

xmodule/xml_block.py

@@ -123,7 +123,11 @@ class XmlMixin:
                          # places in the platform rely on it.
                          'course', 'org', 'url_name', 'filename',
                          # Used for storing xml attributes between import and export, for roundtrips
-                         'xml_attributes')
+                         'xml_attributes',
+                         # Used by _import_xml_node_to_parent in cms/djangoapps/contentstore/helpers.py to prevent
+                         # XmlMixin from treating some XML nodes as "pointer nodes".
+                         "x-is-pointer-node",
+                         )
 
     # This is a categories to fields map that contains the block category specific fields which should not be
     # cleaned and/or override while adding xml to node.