diff -r aac6b313ef5f Lib/pickle.py
--- a/Lib/pickle.py	Sat Nov 24 20:42:59 2012 +0100
+++ b/Lib/pickle.py	Sun Nov 25 13:47:45 2012 +0200
@@ -26,7 +26,6 @@
 from types import FunctionType, BuiltinFunctionType
 from copyreg import dispatch_table
 from copyreg import _extension_registry, _inverted_registry, _extension_cache
-import marshal
 import sys
 import struct
 import re
@@ -58,11 +57,6 @@
 # there are too many issues with that.
 DEFAULT_PROTOCOL = 3
 
-# Why use struct.pack() for pickling but marshal.loads() for
-# unpickling?  struct.pack() is 40% faster than marshal.dumps(), but
-# marshal.loads() is twice as fast as struct.unpack()!
-mloads = marshal.loads
-
 class PickleError(Exception):
     """A common base class for the other pickling exceptions."""
     pass
@@ -231,7 +225,7 @@
             raise PicklingError("Pickler.__init__() was not called by "
                                 "%s.__init__()" % (self.__class__.__name__,))
         if self.proto >= 2:
-            self.write(PROTO + bytes([self.proto]))
+            self.write(PROTO + struct.pack("<B", self.proto))
         self.save(obj)
         self.write(STOP)
 
@@ -261,7 +255,7 @@
     def put(self, i, pack=struct.pack):
         if self.bin:
             if i < 256:
-                return BINPUT + bytes([i])
+                return BINPUT + pack("<B", i)
             else:
                 return LONG_BINPUT + pack("<I", i)
 
@@ -271,7 +265,7 @@
     def get(self, i, pack=struct.pack):
         if self.bin:
             if i < 256:
-                return BINGET + bytes([i])
+                return BINGET + pack("<B", i)
             else:
                 return LONG_BINGET + pack("<I", i)
 
@@ -286,20 +280,20 @@
 
         # Check the memo
         x = self.memo.get(id(obj))
-        if x:
+        if x is not None:
             self.write(self.get(x[0]))
             return
 
         # Check the type dispatch table
         t = type(obj)
         f = self.dispatch.get(t)
-        if f:
+        if f is not None:
             f(self, obj) # Call unbound method with explicit self
             return
 
         # Check private dispatch table if any, or else copyreg.dispatch_table
         reduce = getattr(self, 'dispatch_table', dispatch_table).get(t)
-        if reduce:
+        if reduce is not None:
             rv = reduce(obj)
         else:
             # Check for a class with a custom metaclass; treat as regular class
@@ -313,11 +307,11 @@
 
             # Check for a __reduce_ex__ method, fall back to __reduce__
             reduce = getattr(obj, "__reduce_ex__", None)
-            if reduce:
+            if reduce is not None:
                 rv = reduce(self.proto)
             else:
                 reduce = getattr(obj, "__reduce__", None)
-                if reduce:
+                if reduce is not None:
                     rv = reduce()
                 else:
                     raise PicklingError("Can't pickle %r object: %r" %
@@ -448,9 +442,9 @@
 
     def save_bool(self, obj):
         if self.proto >= 2:
-            self.write(obj and NEWTRUE or NEWFALSE)
+            self.write(NEWTRUE if obj else NEWFALSE)
         else:
-            self.write(obj and TRUE or FALSE)
+            self.write(TRUE if obj else FALSE)
     dispatch[bool] = save_bool
 
     def save_long(self, obj, pack=struct.pack):
@@ -461,23 +455,20 @@
             # First one- and two-byte unsigned ints:
             if obj >= 0:
                 if obj <= 0xff:
-                    self.write(BININT1 + bytes([obj]))
+                    self.write(BININT1 + pack("<B", obj))
                     return
                 if obj <= 0xffff:
-                    self.write(BININT2 + bytes([obj&0xff, obj>>8]))
+                    self.write(BININT2 + pack("<H", obj))
                     return
             # Next check for 4-byte signed ints:
-            high_bits = obj >> 31  # note that Python shift sign-extends
-            if high_bits == 0 or high_bits == -1:
-                # All high bits are copies of bit 2**31, so the value
-                # fits in a 4-byte signed int.
+            if -0x80000000 <= obj <= 0x7fffffff:
                 self.write(BININT + pack("<i", obj))
                 return
         if self.proto >= 2:
             encoded = encode_long(obj)
             n = len(encoded)
             if n < 256:
-                self.write(LONG1 + bytes([n]) + encoded)
+                self.write(LONG1 + pack("<B", n) + encoded)
             else:
                 self.write(LONG4 + pack("<i", n) + encoded)
             return
@@ -501,9 +492,9 @@
             return
         n = len(obj)
         if n < 256:
-            self.write(SHORT_BINBYTES + bytes([n]) + bytes(obj))
+            self.write(SHORT_BINBYTES + pack("<B", n) + obj)
         else:
-            self.write(BINBYTES + pack("<I", n) + bytes(obj))
+            self.write(BINBYTES + pack("<I", n) + obj)
         self.memoize(obj)
     dispatch[bytes] = save_bytes
 
@@ -515,7 +506,7 @@
         else:
             obj = obj.replace("\\", "\\u005c")
             obj = obj.replace("\n", "\\u000a")
-            self.write(UNICODE + bytes(obj.encode('raw-unicode-escape')) +
+            self.write(UNICODE + obj.encode('raw-unicode-escape') +
                        b'\n')
         self.memoize(obj)
     dispatch[str] = save_str
@@ -702,9 +693,9 @@
             if code:
                 assert code > 0
                 if code <= 0xff:
-                    write(EXT1 + bytes([code]))
+                    write(EXT1 + pack("<B", code))
                 elif code <= 0xffff:
-                    write(EXT2 + bytes([code&0xff, code>>8]))
+                    write(EXT2 + pack("<H", code))
                 else:
                     write(EXT4 + pack("<i", code))
                 return
@@ -832,7 +823,7 @@
         read = self.read
         dispatch = self.dispatch
         try:
-            while 1:
+            while True:
                 key = read(1)
                 if not key:
                     raise EOFError
@@ -862,7 +853,7 @@
     dispatch = {}
 
     def load_proto(self):
-        proto = ord(self.read(1))
+        proto = self.read(1)[0]
         if not 0 <= proto <= HIGHEST_PROTOCOL:
             raise ValueError("unsupported pickle protocol: %d" % proto)
         self.proto = proto
@@ -897,23 +888,20 @@
         elif data == TRUE[1:]:
             val = True
         else:
-            try:
-                val = int(data, 0)
-            except ValueError:
-                val = int(data, 0)
+            val = int(data, 0)
         self.append(val)
     dispatch[INT[0]] = load_int
 
-    def load_binint(self):
-        self.append(mloads(b'i' + self.read(4)))
+    def load_binint(self, unpack=struct.unpack):
+        self.append(unpack('<i', self.read(4))[0])
     dispatch[BININT[0]] = load_binint
 
     def load_binint1(self):
-        self.append(ord(self.read(1)))
+        self.append(self.read(1)[0])
     dispatch[BININT1[0]] = load_binint1
 
-    def load_binint2(self):
-        self.append(mloads(b'i' + self.read(2) + b'\000\000'))
+    def load_binint2(self, unpack=struct.unpack):
+        self.append(unpack('<H', self.read(2))[0])
     dispatch[BININT2[0]] = load_binint2
 
     def load_long(self):
@@ -924,13 +912,13 @@
     dispatch[LONG[0]] = load_long
 
     def load_long1(self):
-        n = ord(self.read(1))
+        n = self.read(1)[0]
         data = self.read(n)
         self.append(decode_long(data))
     dispatch[LONG1[0]] = load_long1
 
-    def load_long4(self):
-        n = mloads(b'i' + self.read(4))
+    def load_long4(self, unpack=struct.unpack):
+        n, = unpack('<i', self.read(4))
         if n < 0:
             # Corrupt or hostile pickle -- we never write one like this
             raise UnpicklingError("LONG pickle has negative byte count");
@@ -961,9 +949,9 @@
                     .decode(self.encoding, self.errors))
     dispatch[STRING[0]] = load_string
 
-    def load_binstring(self):
+    def load_binstring(self, unpack=struct.unpack):
         # Deprecated BINSTRING uses signed 32-bit length
-        len = mloads(b'i' + self.read(4))
+        len, = unpack('<i', self.read(4))
         if len < 0:
             raise UnpicklingError("BINSTRING pickle has negative byte count");
         data = self.read(len)
@@ -990,15 +978,15 @@
     dispatch[BINUNICODE[0]] = load_binunicode
 
     def load_short_binstring(self):
-        len = ord(self.read(1))
-        data = bytes(self.read(len))
+        len = self.read(1)[0]
+        data = self.read(len)
         value = str(data, self.encoding, self.errors)
         self.append(value)
     dispatch[SHORT_BINSTRING[0]] = load_short_binstring
 
     def load_short_binbytes(self):
-        len = ord(self.read(1))
-        self.append(bytes(self.read(len)))
+        len = self.read(1)[0]
+        self.append(self.read(len))
     dispatch[SHORT_BINBYTES[0]] = load_short_binbytes
 
     def load_tuple(self):
@@ -1037,12 +1025,9 @@
 
     def load_dict(self):
         k = self.marker()
-        d = {}
         items = self.stack[k+1:]
-        for i in range(0, len(items), 2):
-            key = items[i]
-            value = items[i+1]
-            d[key] = value
+        d = {items[i]: items[i+1]
+             for i in range(0, len(items), 2)}
         self.stack[k:] = [d]
     dispatch[DICT[0]] = load_dict
 
@@ -1094,17 +1079,17 @@
     dispatch[GLOBAL[0]] = load_global
 
     def load_ext1(self):
-        code = ord(self.read(1))
+        code = self.read(1)[0]
         self.get_extension(code)
     dispatch[EXT1[0]] = load_ext1
 
-    def load_ext2(self):
-        code = mloads(b'i' + self.read(2) + b'\000\000')
+    def load_ext2(self, unpack=struct.unpack):
+        code, = unpack('<H', self.read(2))
         self.get_extension(code)
     dispatch[EXT2[0]] = load_ext2
 
-    def load_ext4(self):
-        code = mloads(b'i' + self.read(4))
+    def load_ext4(self, unpack=struct.unpack):
+        code, = unpack('<i', self.read(4))
         self.get_extension(code)
     dispatch[EXT4[0]] = load_ext4
 
@@ -1236,7 +1221,7 @@
         state = stack.pop()
         inst = stack[-1]
         setstate = getattr(inst, "__setstate__", None)
-        if setstate:
+        if setstate is not None:
             setstate(state)
             return
         slotstate = None