diff --git a/requests/packages/urllib3/__init__.py b/requests/packages/urllib3/__init__.py
index d7592ae7..0660b9c8 100644
--- a/requests/packages/urllib3/__init__.py
+++ b/requests/packages/urllib3/__init__.py
@@ -4,7 +4,7 @@ urllib3 - Thread-safe connection pooling and re-using.
 
 __author__ = 'Andrey Petrov (andrey.petrov@shazow.net)'
 __license__ = 'MIT'
-__version__ = 'dev'
+__version__ = '1.10.2'
 
 
 from .connectionpool import (
diff --git a/requests/packages/urllib3/_collections.py b/requests/packages/urllib3/_collections.py
index 06412ddf..cc424de0 100644
--- a/requests/packages/urllib3/_collections.py
+++ b/requests/packages/urllib3/_collections.py
@@ -20,8 +20,6 @@ from .packages.six import iterkeys, itervalues, PY3
 __all__ = ['RecentlyUsedContainer', 'HTTPHeaderDict']
 
 
-MULTIPLE_HEADERS_ALLOWED = frozenset(['cookie', 'set-cookie', 'set-cookie2'])
-
 _Null = object()
 
 
@@ -143,7 +141,10 @@ class HTTPHeaderDict(dict):
     def __init__(self, headers=None, **kwargs):
         dict.__init__(self)
         if headers is not None:
-            self.extend(headers)
+            if isinstance(headers, HTTPHeaderDict):
+                self._copy_from(headers)
+            else:
+                self.extend(headers)
         if kwargs:
             self.extend(kwargs)
 
@@ -223,11 +224,8 @@ class HTTPHeaderDict(dict):
                 vals.append(val)
             else:
                 # vals should be a tuple then, i.e. only one item so far
-                if key_lower in MULTIPLE_HEADERS_ALLOWED:
-                    # Need to convert the tuple to list for further extension
-                    _dict_setitem(self, key_lower, [vals[0], vals[1], val])
-                else:
-                    _dict_setitem(self, key_lower, new_vals)
+                # Need to convert the tuple to list for further extension
+                _dict_setitem(self, key_lower, [vals[0], vals[1], val])
 
     def extend(*args, **kwargs):
         """Generic import function for any type of header-like object.
@@ -276,14 +274,17 @@ class HTTPHeaderDict(dict):
     def __repr__(self):
         return "%s(%s)" % (type(self).__name__, dict(self.itermerged()))
 
-    def copy(self):
-        clone = type(self)()
-        for key in self:
-            val = _dict_getitem(self, key)
+    def _copy_from(self, other):
+        for key in other:
+            val = _dict_getitem(other, key)
             if isinstance(val, list):
                 # Don't need to convert tuples
                 val = list(val)
-            _dict_setitem(clone, key, val)
+            _dict_setitem(self, key, val)
+
+    def copy(self):
+        clone = type(self)()
+        clone._copy_from(self)
         return clone
 
     def iteritems(self):
diff --git a/requests/packages/urllib3/exceptions.py b/requests/packages/urllib3/exceptions.py
index 0c6fd3c5..5d523011 100644
--- a/requests/packages/urllib3/exceptions.py
+++ b/requests/packages/urllib3/exceptions.py
@@ -157,3 +157,8 @@ class InsecureRequestWarning(SecurityWarning):
 class SystemTimeWarning(SecurityWarning):
     "Warned when system time is suspected to be wrong"
     pass
+
+
+class InsecurePlatformWarning(SecurityWarning):
+    "Warned when certain SSL configuration is not available on a platform."
+    pass
diff --git a/requests/packages/urllib3/util/ssl_.py b/requests/packages/urllib3/util/ssl_.py
index ee1d3223..e7e7dfae 100644
--- a/requests/packages/urllib3/util/ssl_.py
+++ b/requests/packages/urllib3/util/ssl_.py
@@ -1,7 +1,7 @@
 from binascii import hexlify, unhexlify
 from hashlib import md5, sha1, sha256
 
-from ..exceptions import SSLError
+from ..exceptions import SSLError, InsecurePlatformWarning
 
 
 SSLContext = None
@@ -10,6 +10,7 @@ create_default_context = None
 
 import errno
 import ssl
+import warnings
 
 try:  # Test for SSL features
     from ssl import wrap_socket, CERT_NONE, PROTOCOL_SSLv23
@@ -69,6 +70,14 @@ except ImportError:
             self.ciphers = cipher_suite
 
         def wrap_socket(self, socket, server_hostname=None):
+            warnings.warn(
+                'A true SSLContext object is not available. This prevents '
+                'urllib3 from configuring SSL appropriately and may cause '
+                'certain SSL connections to fail. For more information, see '
+                'https://urllib3.readthedocs.org/en/latest/security.html'
+                '#insecureplatformwarning.',
+                InsecurePlatformWarning
+            )
             kwargs = {
                 'keyfile': self.keyfile,
                 'certfile': self.certfile,