diff --git a/Lib/json/__init__.py b/Lib/json/__init__.py
index 6d88931..ba2bc1d 100644
--- a/Lib/json/__init__.py
+++ b/Lib/json/__init__.py
@@ -31,7 +31,9 @@
 Compact encoding::
 
     >>> import json
-    >>> json.dumps([1,2,3,{'4': 5, '6': 7}], separators=(',', ':'))
+    >>> from collections import OrderedDict
+    >>> mydict = OrderedDict([('4', 5), ('6', 7)])
+    >>> json.dumps([1,2,3,mydict], separators=(',', ':'))
     '[1,2,3,{"4":5,"6":7}]'
 
 Pretty printing::
diff --git a/Lib/os.py b/Lib/os.py
index a894ee0..5862383 100644
--- a/Lib/os.py
+++ b/Lib/os.py
@@ -761,23 +761,6 @@
 except NameError: # statvfs_result may not exist
     pass
 
-if not _exists("urandom"):
-    def urandom(n):
-        """urandom(n) -> str
-
-        Return a string of n random bytes suitable for cryptographic use.
-
-        """
-        try:
-            _urandomfd = open("/dev/urandom", O_RDONLY)
-        except (OSError, IOError):
-            raise NotImplementedError("/dev/urandom (or equivalent) not found")
-        bs = b""
-        while len(bs) < n:
-            bs += read(_urandomfd, n - len(bs))
-        close(_urandomfd)
-        return bs
-
 # Supply os.popen()
 def popen(cmd, mode="r", buffering=-1):
     if not isinstance(cmd, str):
diff --git a/Lib/test/mapping_tests.py b/Lib/test/mapping_tests.py
index d2b7a59..bc12c77 100644
--- a/Lib/test/mapping_tests.py
+++ b/Lib/test/mapping_tests.py
@@ -14,7 +14,7 @@
     def _reference(self):
         """Return a dictionary of values which are invariant by storage
         in the object under test."""
-        return {1:2, "key1":"value1", "key2":(1,2,3)}
+        return {"1": "2", "key1":"value1", "key2":(1,2,3)}
     def _empty_mapping(self):
         """Return an empty mapping object"""
         return self.type2test()
diff --git a/Lib/test/regrtest.py b/Lib/test/regrtest.py
index 135a90e..26ba982 100755
--- a/Lib/test/regrtest.py
+++ b/Lib/test/regrtest.py
@@ -496,6 +496,11 @@
         except ValueError:
             print("Couldn't find starting test (%s), using all tests" % start)
     if randomize:
+        hashseed = os.getenv('PYTHONHASHSEED')
+        if not hashseed:
+            os.environ['PYTHONHASHSEED'] = str(random_seed)
+            os.execv(sys.executable, [sys.executable] + sys.argv)
+            return
         random.seed(random_seed)
         print("Using random seed", random_seed)
         random.shuffle(selected)
diff --git a/Lib/test/script_helper.py b/Lib/test/script_helper.py
index 371c33d..ba446cd 100644
--- a/Lib/test/script_helper.py
+++ b/Lib/test/script_helper.py
@@ -3,7 +3,6 @@
 
 import sys
 import os
-import re
 import os.path
 import tempfile
 import subprocess
@@ -20,11 +19,15 @@
     cmd_line = [sys.executable]
     if not env_vars:
         cmd_line.append('-E')
-    cmd_line.extend(args)
     # Need to preserve the original environment, for in-place testing of
     # shared library builds.
     env = os.environ.copy()
+    # But a special flag that can be set to override -- in this case, the
+    # caller is responsible to pass the full environment.
+    if env_vars.pop('__cleanenv', None):
+        env = {}
     env.update(env_vars)
+    cmd_line.extend(args)
     p = subprocess.Popen(cmd_line, stdin=subprocess.PIPE,
                          stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                          env=env)
diff --git a/Lib/test/test_cmd_line.py b/Lib/test/test_cmd_line.py
index 2fca25e..1a21281 100644
--- a/Lib/test/test_cmd_line.py
+++ b/Lib/test/test_cmd_line.py
@@ -330,6 +330,22 @@
     def test_no_std_streams(self):
         self._test_no_stdio(['stdin', 'stdout', 'stderr'])
 
+    def test_hash_randomization(self):
+        # Verify that -R enables hash randomization:
+        self.verify_valid_flag('-R')
+        hashes = []
+        for i in range(2):
+            code = 'print(hash("spam"))'
+            rc, out, err = assert_python_ok('-R', '-c', code)
+            self.assertEqual(rc, 0)
+            hashes.append(out)
+        self.assertNotEqual(hashes[0], hashes[1])
+
+        # Verify that sys.flags contains hash_randomization
+        code = 'import sys; print("random is", sys.flags.hash_randomization)'
+        rc, out, err = assert_python_ok('-R', '-c', code)
+        self.assertEqual(rc, 0)
+        self.assertIn(b'random is 1', out)
 
 def test_main():
     test.support.run_unittest(CmdLineTest)
diff --git a/Lib/test/test_descr.py b/Lib/test/test_descr.py
index b214996..77cadc0 100644
--- a/Lib/test/test_descr.py
+++ b/Lib/test/test_descr.py
@@ -4474,8 +4474,18 @@
 
     def test_repr(self):
         # Testing dict_proxy.__repr__
+        def sorted_dict_repr(repr_):
+            # Given the repr of a dict, sort the keys
+            assert repr_.startswith('{')
+            assert repr_.endswith('}')
+            kvs = repr_[1:-1].split(', ')
+            return '{' + ', '.join(sorted(kvs)) + '}'
         dict_ = {k: v for k, v in self.C.__dict__.items()}
-        self.assertEqual(repr(self.C.__dict__), 'dict_proxy({!r})'.format(dict_))
+        repr_ = repr(self.C.__dict__)
+        self.assert_(repr_.startswith('dict_proxy('))
+        self.assert_(repr_.endswith(')'))
+        self.assertEqual(sorted_dict_repr(repr_[len('dict_proxy('):-len(')')]),
+                         sorted_dict_repr('{!r}'.format(dict_)))
 
 
 class PTypesLongInitTest(unittest.TestCase):
diff --git a/Lib/test/test_gdb.py b/Lib/test/test_gdb.py
index 651aaec..aea7c0c 100644
--- a/Lib/test/test_gdb.py
+++ b/Lib/test/test_gdb.py
@@ -52,13 +52,18 @@
 
     """Test that the debugger can debug Python."""
 
-    def run_gdb(self, *args):
+    def run_gdb(self, *args, **env_vars):
         """Runs gdb with the command line given by *args.
 
         Returns its stdout, stderr
         """
+        if env_vars:
+            env = os.environ.copy()
+            env.update(env_vars)
+        else:
+            env = None
         out, err = subprocess.Popen(
-            args, stdout=subprocess.PIPE, stderr=subprocess.PIPE,
+            args, stdout=subprocess.PIPE, stderr=subprocess.PIPE, env=env,
             ).communicate()
         return out.decode('utf-8', 'replace'), err.decode('utf-8', 'replace')
 
@@ -118,7 +123,7 @@
         # print ' '.join(args)
 
         # Use "args" to invoke gdb, capturing stdout, stderr:
-        out, err = self.run_gdb(*args)
+        out, err = self.run_gdb(*args, PYTHONHASHSEED='0')
 
         # Ignore some noise on stderr due to the pending breakpoint:
         err = err.replace('Function "%s" not defined.\n' % breakpoint, '')
@@ -207,7 +212,8 @@
         'Verify the pretty-printing of dictionaries'
         self.assertGdbRepr({})
         self.assertGdbRepr({'foo': 'bar'})
-        self.assertGdbRepr({'foo': 'bar', 'douglas':42})
+        self.assertGdbRepr({'foo': 'bar', 'douglas': 42},
+                           "{'foo': 'bar', 'douglas': 42}")
 
     def test_lists(self):
         'Verify the pretty-printing of lists'
@@ -269,8 +275,8 @@
     def test_sets(self):
         'Verify the pretty-printing of sets'
         self.assertGdbRepr(set())
-        self.assertGdbRepr(set(['a', 'b']))
-        self.assertGdbRepr(set([4, 5, 6]))
+        self.assertGdbRepr(set(['a', 'b']), "{'a', 'b'}")
+        self.assertGdbRepr(set([4, 5, 6]), "{4, 5, 6}")
 
         # Ensure that we handle sets containing the "dummy" key value,
         # which happens on deletion:
@@ -282,8 +288,8 @@
     def test_frozensets(self):
         'Verify the pretty-printing of frozensets'
         self.assertGdbRepr(frozenset())
-        self.assertGdbRepr(frozenset(['a', 'b']))
-        self.assertGdbRepr(frozenset([4, 5, 6]))
+        self.assertGdbRepr(frozenset(['a', 'b']), "frozenset({'a', 'b'})")
+        self.assertGdbRepr(frozenset([4, 5, 6]), "frozenset({4, 5, 6})")
 
     def test_exceptions(self):
         # Test a RuntimeError
diff --git a/Lib/test/test_hash.py b/Lib/test/test_hash.py
index fea1025..8253610 100644
--- a/Lib/test/test_hash.py
+++ b/Lib/test/test_hash.py
@@ -3,10 +3,16 @@
 #
 # Also test that hash implementations are inherited as expected
 
+import datetime
+import os
+import sys
 import unittest
 from test import support
+from test.script_helper import assert_python_ok
 from collections import Hashable
 
+IS_64BIT = sys.maxsize > 2**32
+
 
 class HashEqualityTestCase(unittest.TestCase):
 
@@ -118,10 +124,92 @@
         for obj in self.hashes_to_check:
             self.assertEqual(hash(obj), _default_hash(obj))
 
+class HashRandomizationTests(unittest.TestCase):
+
+    # Each subclass should define a field "repr_", containing the repr() of
+    # an object to be tested
+
+    def get_hash_command(self, repr_):
+        return 'print(hash(%s))' % repr_
+
+    def get_hash(self, repr_, seed=None):
+        env = os.environ.copy()
+        env['__cleanenv'] = True  # signal to assert_python not to do a copy
+                                  # of os.environ on its own
+        if seed is not None:
+            env['PYTHONHASHSEED'] = str(seed)
+        else:
+            env.pop('PYTHONHASHSEED', None)
+        out = assert_python_ok(
+            '-c', self.get_hash_command(repr_),
+            **env)
+        stdout = out[1].strip()
+        return int(stdout)
+
+    def test_randomized_hash(self):
+        # two runs should return different hashes
+        run1 = self.get_hash(self.repr_, seed='random')
+        run2 = self.get_hash(self.repr_, seed='random')
+        self.assertNotEqual(run1, run2)
+
+class StringlikeHashRandomizationTests(HashRandomizationTests):
+    def test_null_hash(self):
+        # PYTHONHASHSEED=0 disables the randomized hash
+        if IS_64BIT:
+            known_hash_of_obj = 1453079729188098211
+        else:
+            known_hash_of_obj = -1600925533
+
+        # Randomization is disabled by default:
+        self.assertEqual(self.get_hash(self.repr_), known_hash_of_obj)
+
+        # It can also be disabled by setting the seed to 0:
+        self.assertEqual(self.get_hash(self.repr_, seed=0), known_hash_of_obj)
+
+    def test_fixed_hash(self):
+        # test a fixed seed for the randomized hash
+        # Note that all types share the same values:
+        if IS_64BIT:
+            h = -4410911502303878509
+        else:
+            h = -206076799
+        self.assertEqual(self.get_hash(self.repr_, seed=42), h)
+
+class StrHashRandomizationTests(StringlikeHashRandomizationTests):
+    repr_ = repr('abc')
+
+    def test_empty_string(self):
+        self.assertEqual(hash(""), 0)
+
+class BytesHashRandomizationTests(StringlikeHashRandomizationTests):
+    repr_ = repr(b'abc')
+
+    def test_empty_string(self):
+        self.assertEqual(hash(b""), 0)
+
+class DatetimeTests(HashRandomizationTests):
+    def get_hash_command(self, repr_):
+        return 'import datetime; print(hash(%s))' % repr_
+
+class DatetimeDateTests(DatetimeTests):
+    repr_ = repr(datetime.date(1066, 10, 14))
+
+class DatetimeDatetimeTests(DatetimeTests):
+    repr_ = repr(datetime.datetime(1, 2, 3, 4, 5, 6, 7))
+
+class DatetimeTimeTests(DatetimeTests):
+    repr_ = repr(datetime.time(0))
+
+
 def test_main():
     support.run_unittest(HashEqualityTestCase,
-                              HashInheritanceTestCase,
-                              HashBuiltinsTestCase)
+                         HashInheritanceTestCase,
+                         HashBuiltinsTestCase,
+                         StrHashRandomizationTests,
+                         BytesHashRandomizationTests,
+                         DatetimeDateTests,
+                         DatetimeDatetimeTests,
+                         DatetimeTimeTests)
 
 
 if __name__ == "__main__":
diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
index e573bd2..8bc8ba9 100644
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -15,6 +15,7 @@
 import contextlib
 import mmap
 import uuid
+from test.script_helper import assert_python_ok
 
 # Detect whether we're on a Linux system that uses the (now outdated
 # and unmaintained) linuxthreads threading library.  There's an issue
@@ -611,14 +612,33 @@
             self.assertEqual(f.read(), b'')
 
 class URandomTests(unittest.TestCase):
-    def test_urandom(self):
-        try:
-            self.assertEqual(len(os.urandom(1)), 1)
-            self.assertEqual(len(os.urandom(10)), 10)
-            self.assertEqual(len(os.urandom(100)), 100)
-            self.assertEqual(len(os.urandom(1000)), 1000)
-        except NotImplementedError:
-            pass
+    def test_urandom_length(self):
+        self.assertEqual(len(os.urandom(0)), 0)
+        self.assertEqual(len(os.urandom(1)), 1)
+        self.assertEqual(len(os.urandom(10)), 10)
+        self.assertEqual(len(os.urandom(100)), 100)
+        self.assertEqual(len(os.urandom(1000)), 1000)
+
+    def test_urandom_value(self):
+        data1 = os.urandom(16)
+        data2 = os.urandom(16)
+        self.assertNotEqual(data1, data2)
+
+    def get_urandom_subprocess(self, count):
+        code = '\n'.join((
+            'import os, sys',
+            'data = os.urandom(%s)' % count,
+            'sys.stdout.buffer.write(data)',
+            'sys.stdout.buffer.flush()'))
+        out = assert_python_ok('-c', code)
+        stdout = out[1]
+        self.assertEqual(len(stdout), 16)
+        return stdout
+
+    def test_urandom_subprocess(self):
+        data1 = self.get_urandom_subprocess(16)
+        data2 = self.get_urandom_subprocess(16)
+        self.assertNotEqual(data1, data2)
 
 @contextlib.contextmanager
 def _execvpe_mockup(defpath=None):
diff --git a/Lib/test/test_set.py b/Lib/test/test_set.py
index 07bfe06..6642440 100644
--- a/Lib/test/test_set.py
+++ b/Lib/test/test_set.py
@@ -733,6 +733,17 @@
         if self.repr is not None:
             self.assertEqual(repr(self.set), self.repr)
 
+    def check_repr_against_values(self):
+        text = repr(self.set)
+        self.assertTrue(text.startswith('{'))
+        self.assertTrue(text.endswith('}'))
+
+        result = text[1:-1].split(', ')
+        result.sort()
+        sorted_repr_values = [repr(value) for value in self.values]
+        sorted_repr_values.sort()
+        self.assertEqual(result, sorted_repr_values)
+
     def test_print(self):
         try:
             fo = open(support.TESTFN, "w")
@@ -891,7 +902,9 @@
         self.set    = set(self.values)
         self.dup    = set(self.values)
         self.length = 3
-        self.repr   = "{'a', 'c', 'b'}"
+
+    def test_repr(self):
+        self.check_repr_against_values()
 
 #------------------------------------------------------------------------------
 
@@ -902,7 +915,9 @@
         self.set    = set(self.values)
         self.dup    = set(self.values)
         self.length = 3
-        self.repr   = "{b'a', b'c', b'b'}"
+
+    def test_repr(self):
+        self.check_repr_against_values()
 
 #------------------------------------------------------------------------------
 
@@ -916,11 +931,13 @@
         self.set    = set(self.values)
         self.dup    = set(self.values)
         self.length = 4
-        self.repr   = "{'a', b'a', 'b', b'b'}"
 
     def tearDown(self):
         self._warning_filters.__exit__(None, None, None)
 
+    def test_repr(self):
+        self.check_repr_against_values()
+
 #==============================================================================
 
 def baditer():
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 5d3404f..3268b1a 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -503,7 +503,7 @@
         attrs = ("debug", "division_warning",
                  "inspect", "interactive", "optimize", "dont_write_bytecode",
                  "no_user_site", "no_site", "ignore_environment", "verbose",
-                 "bytes_warning", "quiet")
+                 "bytes_warning", "quiet", "hash_randomization")
         for attr in attrs:
             self.assertTrue(hasattr(sys.flags, attr), attr)
             self.assertEqual(type(getattr(sys.flags, attr)), int, attr)
diff --git a/Lib/test/test_urllib.py b/Lib/test/test_urllib.py
index f6b48cb..c6f6f61 100644
--- a/Lib/test/test_urllib.py
+++ b/Lib/test/test_urllib.py
@@ -13,6 +13,7 @@
 import tempfile
 
 from base64 import b64encode
+import collections
 
 def hexescape(char):
     """Escape char as RFC 2396 specifies"""
@@ -953,8 +954,9 @@
         self.assertEqual("a=1&a=2", urllib.parse.urlencode({"a": [1, 2]}, True))
         self.assertEqual("a=None&a=a",
                          urllib.parse.urlencode({"a": [None, "a"]}, True))
+        data = collections.OrderedDict([("a", 1), ("b", 1)])
         self.assertEqual("a=a&a=b",
-                         urllib.parse.urlencode({"a": {"a": 1, "b": 1}}, True))
+                         urllib.parse.urlencode({"a": data}, True))
 
     def test_urlencode_encoding(self):
         # ASCII encoding. Expect %3F with errors="replace'
diff --git a/Lib/test/test_urlparse.py b/Lib/test/test_urlparse.py
old mode 100644
new mode 100755
index a6e7ee8..ada0ca8
--- a/Lib/test/test_urlparse.py
+++ b/Lib/test/test_urlparse.py
@@ -769,7 +769,8 @@
         # Other tests incidentally urlencode things; test non-covered cases:
         # Sequence and object values.
         result = urllib.parse.urlencode({'a': [1, 2], 'b': (3, 4, 5)}, True)
-        self.assertEqual(result, 'a=1&a=2&b=3&b=4&b=5')
+        # we cannot rely on ordering here
+        assert set(result.split('&')) == {'a=1', 'a=2', 'b=3', 'b=4', 'b=5'}
 
         class Trivial:
             def __str__(self):
diff --git a/Lib/tkinter/test/test_ttk/test_functions.py b/Lib/tkinter/test/test_ttk/test_functions.py
index df593cd..2303e4c 100644
--- a/Lib/tkinter/test/test_ttk/test_functions.py
+++ b/Lib/tkinter/test/test_ttk/test_functions.py
@@ -143,7 +143,7 @@
             ('a', 'b', 'c')), ("test {a b} c", ()))
         # state spec and options
         self.assertEqual(ttk._format_elemcreate('image', False, 'test',
-            ('a', 'b'), a='x', b='y'), ("test a b", ("-a", "x", "-b", "y")))
+            ('a', 'b'), a='x'), ("test a b", ("-a", "x")))
         # format returned values as a tcl script
         # state spec with multiple states and an option with a multivalue
         self.assertEqual(ttk._format_elemcreate('image', True, 'test',