combined patches from http://bugs.python.org/issue3187

Lib/io.py

 """The io module provides the Python interfaces to stream handling. The
 builtin open function is defined in this module.
 
 At the top of the I/O hierarchy is the abstract base class IOBase. It
 defines the basic interface to a stream. Note, however, that there is no
 seperation between reading and writing to streams; implementations are
 allowed to throw an IOError if they do not support a given operation.
 
 Extending IOBase is RawIOBase which deals simply with the reading and
 writing of raw bytes to a stream. FileIO subclasses RawIOBase to provide
@@ skipping 162 matching lines @@
     a file in a binary mode, the returned class varies: in read binary
     mode, it returns a BufferedReader; in write binary and append binary
     modes, it returns a BufferedWriter, and in read/write mode, it returns
     a BufferedRandom.
 
     It is also possible to use a string or bytearray as a file for both
     reading and writing. For strings StringIO can be used like a file
     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)
     if buffering is not None and not isinstance(buffering, int):
         raise TypeError("invalid buffering: %r" % buffering)
     if encoding is not None and not isinstance(encoding, str):
         raise TypeError("invalid encoding: %r" % encoding)
     if errors is not None and not isinstance(errors, str):
         raise TypeError("invalid errors: %r" % errors)
     modes = set(mode)
@@ skipping 1933 matching lines @@
                     ("\r", "\n"),
                     "\r\n",
                     ("\n", "\r\n"),
                     ("\r", "\r\n"),
                     ("\r", "\n", "\r\n")
                    )[self._seennl]
 
 
 except ImportError:
     StringIO = _StringIO