Ticket #8908: fix_modelform_unique_check.diff

forms/models.py

@@ -216 +216 @@
         # Make sure the unique checks apply to actual fields on the ModelForm
         for name, field in self.fields.items():
             try:
-                f = self.instance._meta.get_field_by_name(name)[0]
+                field = self.instance._meta.get_field_by_name(name)
+                if not field[2]:
+                    raise FieldDoesNotExist
+                else:
+                    f = field[0]
             except FieldDoesNotExist:
                 # This is an extra field that's not on the ModelForm, ignore it
                 continue