check possible recursive _as_parameter_ to prevent segfault (closes #1838)
diff --git a/Lib/lib2to3/refactor.py b/Lib/lib2to3/refactor.py
index 7d00d12..30aea63 100644
--- a/Lib/lib2to3/refactor.py
+++ b/Lib/lib2to3/refactor.py
@@ -500,7 +500,7 @@
                         node = new
 
     def processed_file(self, new_text, filename, old_text=None, write=False,
-                       encoding=None):
+                       encoding=None, newlines=None):
         """
         Called when a file has been refactored, and there are changes.
         """