Provide clarification on specific page usage for autocreate_redirects_on_slug_change()

wagtail/contrib/redirects/signal_handlers.py

@@ -35,6 +35,9 @@ def autocreate_redirects_on_slug_change(
     instance: Page,
     **kwargs
 ):
+    # NB: `page_slug_changed` provides specific page instances,
+    # so we do not need to 'upcast' them for create_redirects here
+
     if not getattr(settings, "WAGTAILREDIRECTS_AUTO_CREATE", True):
         return None
 

wagtail/core/models/__init__.py

@@ -493,7 +493,8 @@ class Page(AbstractPage, index.Indexed, ClusterableModel, metaclass=PageBase):
             # Basically: If update_fields has been specified, and slug is not included, skip this step
             if not ('update_fields' in kwargs and 'slug' not in kwargs['update_fields']):
                 # see if the slug has changed from the record in the db, in which case we need to
-                # update url_path of self and all descendants
+                # update url_path of self and all descendants. Even though we might not need it,
+                # the specific page is fetched here for sending to the 'page_slug_changed' signal.
                 old_record = Page.objects.get(id=self.id).specific
                 if old_record.slug != self.slug:
                     self.set_url_path(self.get_parent())