Ticket #10643: formtools_utils.diff

django/contrib/formtools/utils.py

@@ -15 +15 @@
     order, pickles the result with the SECRET_KEY setting, then takes an md5
     hash of that.
     """
-
-    data = [(bf.name, bf.field.clean(bf.data) or '') for bf in form]
+    if form.empty_permitted and not form.has_changed():
+        data = [(bf.name, bf.data or '') for bf in form]
+    else:
+        data = [(bf.name, bf.field.clean(bf.data) or '') for bf in form]
     data.extend(args)
     data.append(settings.SECRET_KEY)