Correctly manage filename_field when clearing Binary fields

Introduced in changeset 0764dd5c004f

issue5646
review25241002

tryton/gui/window/view_form/view/list_gtk/widget.py

@@ -501,8 +501,9 @@ class Binary(GenericText):
 
     def clear_binary(self, renderer, path):
         record, field = self._get_record_field(path)
-        if self.filename_field:
-            self.filename_field.set_client(record, None)
+        if self.filename:
+            filename_field = record.group.fields[self.filename]
+            filename_field.set_client(record, None)
         field.set_client(record, None)