Add missing initializer for self._backupfilename. Due to Ralph Butler.

gvanrossum · gvanrossum · commit 0aec9fb1830b · 1998-07-20T15:49:28.000Z
diff --git a/Lib/fileinput.py b/Lib/fileinput.py
@@ -142,6 +142,7 @@ def __init__(self, files=(), inplace=0, backup=""):
         self._filelineno = 0
         self._file = None
         self._isstdin = 0
+        self._backupfilename = None
 
     def __del__(self):
         self.close()
