fix doc fragments (#33892)

* fix doc fragments

fixes #33864

* pop it

lib/ansible/utils/plugin_docs.py

@@ -56,12 +56,13 @@ def merge_fragment(target, source):
                 value = sorted(frozenset(value + target[key]))
             else:
                 raise Exception("Attempt to extend a documentation fragement, invalid type for %s" % key)
+        else:
             target[key] = value
 
 
 def add_fragments(doc, filename):
 
-    fragments = doc.get('extends_documentation_fragment', [])
+    fragments = doc.pop('extends_documentation_fragment', [])
 
     if isinstance(fragments, string_types):
         fragments = [fragments]