diff -r 336a614f35a3 Lib/pickle.py
--- a/Lib/pickle.py	Sun Feb 19 10:17:30 2012 -0500
+++ b/Lib/pickle.py	Sun Feb 19 20:01:08 2012 +0100
@@ -174,7 +174,7 @@
 
 class _Pickler:
 
-    def __init__(self, file, protocol=None, *, fix_imports=True):
+    def __init__(self, file, protocol=None, *, fix_imports=True, bytestr=False):
         """This takes a binary file for writing a pickle data stream.
 
         The optional protocol argument tells the pickler to use the
@@ -195,6 +195,9 @@
         If fix_imports is True and protocol is less than 3, pickle will try to
         map the new Python 3.x names to the old module names used in Python
         2.x, so that the pickle data stream is readable with Python 2.x.
+
+        If bytestr is True and protocol is less than 3, bytes will be stored as
+        8-bit string instead of as bytes object.
         """
         if protocol is None:
             protocol = DEFAULT_PROTOCOL
@@ -211,6 +214,7 @@
         self.bin = protocol >= 1
         self.fast = 0
         self.fix_imports = fix_imports and protocol < 3
+        self.bytestr = bytestr and protocol < 3
 
     def clear_memo(self):
         """Clears the pickler's "memo".
@@ -483,7 +487,7 @@
             self.write(FLOAT + repr(obj).encode("ascii") + b'\n')
     dispatch[float] = save_float
 
-    def save_bytes(self, obj, pack=struct.pack):
+    def save_bytes_as_bytes(self, obj, pack=struct.pack):
         if self.proto < 3:
             if len(obj) == 0:
                 self.save_reduce(bytes, (), obj=obj)
@@ -497,6 +501,24 @@
         else:
             self.write(BINBYTES + pack("<i", n) + bytes(obj))
         self.memoize(obj)
+
+    def save_bytes_as_string(self, obj, pack=struct.pack):
+        if self.bin:
+            n = len(obj)
+            if n < 256:
+                self.write(SHORT_BINSTRING + chr(n).encode('latin-1') + obj)
+            else:
+                self.write(BINSTRING + pack("<i", n) + obj)
+        else:
+            self.write(STRING + repr(obj).lstrip('b').encode('ascii') + b'\n')
+        self.memoize(obj)
+
+    def save_bytes(self, obj, pack=struct.pack):
+        if self.bytestr:
+            return self.save_bytes_as_string(obj, pack)
+        else:
+            return self.save_bytes_as_bytes(obj, pack)
+
     dispatch[bytes] = save_bytes
 
     def save_str(self, obj, pack=struct.pack):
@@ -779,7 +801,7 @@
 class _Unpickler:
 
     def __init__(self, file, *, fix_imports=True,
-                 encoding="ASCII", errors="strict"):
+                 encoding="ASCII", errors="strict", bytestr=False):
         """This takes a binary file for reading a pickle data stream.
 
         The protocol version of the pickle is detected automatically, so no
@@ -792,13 +814,15 @@
         reading, a BytesIO object, or any other custom object that
         meets this interface.
 
-        Optional keyword arguments are *fix_imports*, *encoding* and *errors*,
-        which are used to control compatiblity support for pickle stream
-        generated by Python 2.x.  If *fix_imports* is True, pickle will try to
-        map the old Python 2.x names to the new names used in Python 3.x.  The
-        *encoding* and *errors* tell pickle how to decode 8-bit string
-        instances pickled by Python 2.x; these default to 'ASCII' and
-        'strict', respectively.
+        Optional keyword arguments are *fix_imports*, *encoding*, *errors*
+        and *bytestr*, which are used to control compatiblity support for
+        pickle stream generated by Python 2.x.  If *fix_imports* is True,
+        pickle will try to map the old Python 2.x names to the new names used
+        in Python 3.x.  The *encoding* and *errors* tell pickle how to decode
+        8-bit string instances pickled by Python 2.x; these default to 'ASCII'
+        and 'strict', respectively. If *bytestr* if True, 8-bit string instances
+        will be mapped to bytes instead, and *encoding* and *errors* will be
+        ignored.
         """
         self.readline = file.readline
         self.read = file.read
@@ -807,6 +831,7 @@
         self.errors = errors
         self.proto = 0
         self.fix_imports = fix_imports
+        self.bytestr = bytestr
 
     def load(self):
         """Read a pickled object representation from the open file.
@@ -935,6 +960,12 @@
         self.append(unpack('>d', self.read(8))[0])
     dispatch[BINFLOAT[0]] = load_binfloat
 
+    def decode_string(self, value):
+        if self.bytestr:
+            return value
+        else:
+            return value.decode(self.encoding, self.errors)
+
     def load_string(self):
         orig = self.readline()
         rep = orig[:-1]
@@ -946,15 +977,13 @@
                 break
         else:
             raise ValueError("insecure string pickle: %r" % orig)
-        self.append(codecs.escape_decode(rep)[0]
-                    .decode(self.encoding, self.errors))
+        self.append(self.decode_string(codecs.escape_decode(rep)[0]))
     dispatch[STRING[0]] = load_string
 
     def load_binstring(self):
         len = mloads(b'i' + self.read(4))
         data = self.read(len)
-        value = str(data, self.encoding, self.errors)
-        self.append(value)
+        self.append(self.decode_string(data))
     dispatch[BINSTRING[0]] = load_binstring
 
     def load_binbytes(self):
@@ -973,9 +1002,8 @@
 
     def load_short_binstring(self):
         len = ord(self.read(1))
-        data = bytes(self.read(len))
-        value = str(data, self.encoding, self.errors)
-        self.append(value)
+        data = self.read(len)
+        self.append(self.decode_string(data))
     dispatch[SHORT_BINSTRING[0]] = load_short_binstring
 
     def load_short_binbytes(self):