Issue #13703: add a way to randomize the hash values of basic types (str, bytes, datetime)
in order to make algorithmic complexity attacks on (e.g.) web apps much more complicated.

The environment variable PYTHONHASHSEED and the new command line flag -R control this
behavior.
diff --git a/Lib/test/test_urllib.py b/Lib/test/test_urllib.py
index 4d3509a..482acc1 100644
--- a/Lib/test/test_urllib.py
+++ b/Lib/test/test_urllib.py
@@ -12,6 +12,7 @@
 import sys
 import tempfile
 import warnings
+import collections
 
 def hexescape(char):
     """Escape char as RFC 2396 specifies"""
@@ -840,8 +841,9 @@
         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'