Index: Lib/io.py
===================================================================
--- Lib/io.py	(révision 65973)
+++ Lib/io.py	(copie de travail)
@@ -180,7 +180,7 @@
     opened in a text mode, and for bytes a BytesIO can be used like a file
     opened in a binary mode.
     """
-    if not isinstance(file, (str, int)):
+    if not isinstance(file, (str, bytes, int)):
         raise TypeError("invalid file: %r" % file)
     if not isinstance(mode, str):
         raise TypeError("invalid mode: %r" % mode)