diff --git a/Lib/email/mime/multipart.py b/Lib/email/mime/multipart.py
index 5c8c9db..9661865 100644
--- a/Lib/email/mime/multipart.py
+++ b/Lib/email/mime/multipart.py
@@ -34,6 +34,12 @@
         keyword arguments (or passed into the _params argument).
         """
         MIMEBase.__init__(self, 'multipart', _subtype, **_params)
+
+        # Initialise _payload to an empty list as the Message superclass's
+        # implementation of is_multipart assumes that _payload is a list for
+        # multipart messages.
+        self._payload = []
+
         if _subparts:
             for p in _subparts:
                 self.attach(p)
diff --git a/Lib/email/test/test_email.py b/Lib/email/test/test_email.py
index c544004..1ca41e9 100644
--- a/Lib/email/test/test_email.py
+++ b/Lib/email/test/test_email.py
@@ -1892,6 +1892,9 @@
         eq(msg.get_payload(0), text1)
         eq(msg.get_payload(1), text2)
 
+    def test_default_multipart_constructor(self):
+        msg = MIMEMultipart()
+        self.assertTrue(msg.is_multipart())
 
 
 # A general test of parser->model->generator idempotency.  IOW, read a message
diff --git a/Lib/rational.py b/Lib/rational.py
index c913ec7..71ffff7 100755
--- a/Lib/rational.py
+++ b/Lib/rational.py
@@ -6,6 +6,7 @@
 import math
 import numbers
 import operator
+import re
 
 __all__ = ["Rational"]
 
@@ -75,6 +76,10 @@
         return (top, 2 ** -e)
 
 
+_RATIONAL_FORMAT = re.compile(
+    r'^\s*(?P<sign>[-+]?)(?P<num>\d+)(?:/(?P<denom>\d+))?\s*$')
+
+
 class Rational(RationalAbc):
     """This class implements rational numbers.
 
@@ -83,18 +88,41 @@
     and the denominator defaults to 1 so that Rational(3) == 3 and
     Rational() == 0.
 
+    Rationals can also be constructed from strings of the form
+    '[-+]?[0-9]+(/[0-9]+)?', optionally surrounded by spaces.
+
     """
 
     __slots__ = ('_numerator', '_denominator')
 
-    def __init__(self, numerator=0, denominator=1):
-        if (not isinstance(numerator, numbers.Integral) and
-            isinstance(numerator, RationalAbc) and
-            denominator == 1):
-            # Handle copies from other rationals.
-            other_rational = numerator
-            numerator = other_rational.numerator
-            denominator = other_rational.denominator
+    # We're immutable, so use __new__ not __init__
+    def __new__(cls, numerator=0, denominator=1):
+        """Constructs a Rational.
+
+        Takes a string, another Rational, or a numerator/denominator pair.
+
+        """
+        self = super(Rational, cls).__new__(cls)
+
+        if denominator == 1:
+            if isinstance(numerator, str):
+                # Handle construction from strings.
+                input = numerator
+                m = _RATIONAL_FORMAT.match(input)
+                if m is None:
+                    raise ValueError('Invalid literal for Rational: ' + input)
+                numerator = int(m.group('num'))
+                # Default denominator to 1. That's the only optional group.
+                denominator = int(m.group('denom') or 1)
+                if m.group('sign') == '-':
+                    numerator = -numerator
+
+            elif (not isinstance(numerator, numbers.Integral) and
+                  isinstance(numerator, RationalAbc)):
+                # Handle copies from other rationals.
+                other_rational = numerator
+                numerator = other_rational.numerator
+                denominator = other_rational.denominator
 
         if (not isinstance(numerator, numbers.Integral) or
             not isinstance(denominator, numbers.Integral)):
@@ -107,10 +135,15 @@
         g = _gcd(numerator, denominator)
         self._numerator = int(numerator // g)
         self._denominator = int(denominator // g)
+        return self
 
     @classmethod
     def from_float(cls, f):
-        """Converts a float to a rational number, exactly."""
+        """Converts a finite float to a rational number, exactly.
+
+        Beware that Rational.from_float(0.3) != Rational(3, 10).
+
+        """
         if not isinstance(f, float):
             raise TypeError("%s.from_float() only takes floats, not %r (%s)" %
                             (cls.__name__, f, type(f).__name__))
@@ -118,6 +151,26 @@
             raise TypeError("Cannot convert %r to %s." % (f, cls.__name__))
         return cls(*_binary_float_to_ratio(f))
 
+    @classmethod
+    def from_decimal(cls, dec):
+        """Converts a finite Decimal instance to a rational number, exactly."""
+        from decimal import Decimal
+        if not isinstance(dec, Decimal):
+            raise TypeError(
+                "%s.from_decimal() only takes Decimals, not %r (%s)" %
+                (cls.__name__, dec, type(dec).__name__))
+        if not dec.is_finite():
+            # Catches infinities and nans.
+            raise TypeError("Cannot convert %s to %s." % (dec, cls.__name__))
+        sign, digits, exp = dec.as_tuple()
+        digits = int(''.join(map(str, digits)))
+        if sign:
+            digits = -digits
+        if exp >= 0:
+            return cls(digits * 10 ** exp)
+        else:
+            return cls(digits, 10 ** -exp)
+
     @property
     def numerator(a):
         return a._numerator
@@ -128,15 +181,14 @@
 
     def __repr__(self):
         """repr(self)"""
-        return ('rational.Rational(%r,%r)' %
-                (self.numerator, self.denominator))
+        return ('Rational(%r,%r)' % (self.numerator, self.denominator))
 
     def __str__(self):
         """str(self)"""
         if self.denominator == 1:
             return str(self.numerator)
         else:
-            return '(%s/%s)' % (self.numerator, self.denominator)
+            return '%s/%s' % (self.numerator, self.denominator)
 
     def _operator_fallbacks(monomorphic_operator, fallback_operator):
         """Generates forward and reverse operators given a purely-rational
diff --git a/Lib/test/crashers/weakref_in_del.py b/Lib/test/crashers/weakref_in_del.py
deleted file mode 100644
index 2e9b186..0000000
--- a/Lib/test/crashers/weakref_in_del.py
+++ /dev/null
@@ -1,17 +0,0 @@
-import weakref
-
-# http://python.org/sf/1377858
-# Fixed for new-style classes in 2.5c1.
-
-ref = None
-
-def test_weakref_in_del():
-    class Target():
-        def __del__(self):
-            global ref
-            ref = weakref.ref(self)
-
-    w = Target()
-
-if __name__ == '__main__':
-    test_weakref_in_del()
diff --git a/Lib/test/test_rational.py b/Lib/test/test_rational.py
index 952a97f..e57adce 100644
--- a/Lib/test/test_rational.py
+++ b/Lib/test/test_rational.py
@@ -45,6 +45,44 @@
         self.assertRaises(TypeError, R, 1.5)
         self.assertRaises(TypeError, R, 1.5 + 3j)
 
+        self.assertRaises(TypeError, R, R(1, 2), 3)
+        self.assertRaises(TypeError, R, "3/2", 3)
+
+    def testFromString(self):
+        self.assertEquals((5, 1), _components(R("5")))
+        self.assertEquals((3, 2), _components(R("3/2")))
+        self.assertEquals((3, 2), _components(R(" \n  +3/2")))
+        self.assertEquals((-3, 2), _components(R("-3/2  ")))
+        self.assertEquals((3, 2), _components(R("    03/02 \n  ")))
+        self.assertEquals((3, 2), _components(R("    03/02 \n  ")))
+
+        self.assertRaisesMessage(
+            ZeroDivisionError, "Rational(3, 0)",
+            R, "3/0")
+        self.assertRaisesMessage(
+            ValueError, "Invalid literal for Rational: 3/",
+            R, "3/")
+        self.assertRaisesMessage(
+            ValueError, "Invalid literal for Rational: 3 /2",
+            R, "3 /2")
+        self.assertRaisesMessage(
+            # Denominators don't need a sign.
+            ValueError, "Invalid literal for Rational: 3/+2",
+            R, "3/+2")
+        self.assertRaisesMessage(
+            # Imitate float's parsing.
+            ValueError, "Invalid literal for Rational: + 3/2",
+            R, "+ 3/2")
+        self.assertRaisesMessage(
+            # Only parse fractions, not decimals.
+            ValueError, "Invalid literal for Rational: 3.2",
+            R, "3.2")
+
+    def testImmutable(self):
+        r = R(7, 3)
+        r.__init__(2, 15)
+        self.assertEquals((7, 3), _components(r))
+
     def testFromFloat(self):
         self.assertRaisesMessage(
             TypeError, "Rational.from_float() only takes floats, not 3 (int)",
@@ -72,6 +110,31 @@
             TypeError, "Cannot convert nan to Rational.",
             R.from_float, nan)
 
+    def testFromDecimal(self):
+        self.assertRaisesMessage(
+            TypeError,
+            "Rational.from_decimal() only takes Decimals, not 3 (int)",
+            R.from_decimal, 3)
+        self.assertEquals(R(0), R.from_decimal(Decimal("-0")))
+        self.assertEquals(R(5, 10), R.from_decimal(Decimal("0.5")))
+        self.assertEquals(R(5, 1000), R.from_decimal(Decimal("5e-3")))
+        self.assertEquals(R(5000), R.from_decimal(Decimal("5e3")))
+        self.assertEquals(1 - R(1, 10**30),
+                          R.from_decimal(Decimal("0." + "9" * 30)))
+
+        self.assertRaisesMessage(
+            TypeError, "Cannot convert Infinity to Rational.",
+            R.from_decimal, Decimal("inf"))
+        self.assertRaisesMessage(
+            TypeError, "Cannot convert -Infinity to Rational.",
+            R.from_decimal, Decimal("-inf"))
+        self.assertRaisesMessage(
+            TypeError, "Cannot convert NaN to Rational.",
+            R.from_decimal, Decimal("nan"))
+        self.assertRaisesMessage(
+            TypeError, "Cannot convert sNaN to Rational.",
+            R.from_decimal, Decimal("snan"))
+
     def testConversions(self):
         self.assertTypedEquals(-1, trunc(R(-11, 10)))
         self.assertTypedEquals(-2, math.floor(R(-11, 10)))
@@ -175,7 +238,7 @@
         self.assertTypedEquals(1.0 + 0j, (1.0 + 0j) ** R(1, 10))
 
     def testMixingWithDecimal(self):
-        """Decimal refuses mixed comparisons."""
+        # Decimal refuses mixed comparisons.
         self.assertRaisesMessage(
             TypeError,
             "unsupported operand type(s) for +: 'Rational' and 'Decimal'",
@@ -238,8 +301,8 @@
         self.assertFalse(R(5, 2) == 2)
 
     def testStringification(self):
-        self.assertEquals("rational.Rational(7,3)", repr(R(7, 3)))
-        self.assertEquals("(7/3)", str(R(7, 3)))
+        self.assertEquals("Rational(7,3)", repr(R(7, 3)))
+        self.assertEquals("7/3", str(R(7, 3)))
         self.assertEquals("7", str(R(7, 1)))
 
     def testHash(self):
diff --git a/Lib/test/test_threading_local.py b/Lib/test/test_threading_local.py
index 0aaedbc..b7dd538 100644
--- a/Lib/test/test_threading_local.py
+++ b/Lib/test/test_threading_local.py
@@ -1,9 +1,51 @@
 import unittest
 from doctest import DocTestSuite
 from test import test_support
+import threading
+import weakref
+import gc
+
+class Weak(object):
+    pass
+
+def target(local, weaklist):
+    weak = Weak()
+    local.weak = weak
+    weaklist.append(weakref.ref(weak))
+
+class ThreadingLocalTest(unittest.TestCase):
+
+    def test_local_refs(self):
+        self._local_refs(20)
+        self._local_refs(50)
+        self._local_refs(100)
+
+    def _local_refs(self, n):
+        local = threading.local()
+        weaklist = []
+        for i in range(n):
+            t = threading.Thread(target=target, args=(local, weaklist))
+            t.start()
+            t.join()
+        del t
+
+        gc.collect()
+        self.assertEqual(len(weaklist), n)
+
+        # XXX threading.local keeps the local of the last stopped thread alive.
+        deadlist = [weak for weak in weaklist if weak() is None]
+        self.assertEqual(len(deadlist), n-1)
+
+        # Assignment to the same thread local frees it sometimes (!)
+        local.someothervar = None
+        gc.collect()
+        deadlist = [weak for weak in weaklist if weak() is None]
+        self.assert_(len(deadlist) in (n-1, n), (n, len(deadlist)))
 
 def test_main():
-    suite = DocTestSuite('_threading_local')
+    suite = unittest.TestSuite()
+    suite.addTest(DocTestSuite('_threading_local'))
+    suite.addTest(unittest.makeSuite(ThreadingLocalTest))
 
     try:
         from thread import _local