Prioritize system-installed urllib3 over requests vendored urllib3.

docker/ssladapter/ssladapter.py

@@ -6,9 +6,9 @@ from distutils.version import StrictVersion
 from requests.adapters import HTTPAdapter
 import ssl
 try:
-    import requests.packages.urllib3 as urllib3
-except ImportError:
     import urllib3
+except ImportError:
+    import requests.packages.urllib3 as urllib3
 
 
 PoolManager = urllib3.poolmanager.PoolManager

docker/unixconn/unixconn.py

@@ -21,14 +21,9 @@ import requests.adapters
 import socket
 
 try:
-    import requests.packages.urllib3.connectionpool as connectionpool
+    import urllib3
 except ImportError:
-    import urllib3.connectionpool as connectionpool
-
-try:
-    from requests.packages.urllib3._collections import RecentlyUsedContainer
-except ImportError:
-    from urllib3._collections import RecentlyUsedContainer
+    import requests.packages.urllib3 as urllib3
 
 
 class UnixHTTPConnection(httplib.HTTPConnection, object):
@@ -53,10 +48,11 @@ class UnixHTTPConnection(httplib.HTTPConnection, object):
         super(UnixHTTPConnection, self).request(method, url, **kwargs)
 
 
-class UnixHTTPConnectionPool(connectionpool.HTTPConnectionPool):
+class UnixHTTPConnectionPool(urllib3.connectionpool.HTTPConnectionPool):
     def __init__(self, base_url, socket_path, timeout=60):
-        connectionpool.HTTPConnectionPool.__init__(self, 'localhost',
-                                                   timeout=timeout)
+        urllib3.connectionpool.HTTPConnectionPool.__init__(
+            self, 'localhost', timeout=timeout
+        )
         self.base_url = base_url
         self.socket_path = socket_path
         self.timeout = timeout
@@ -68,6 +64,7 @@ class UnixHTTPConnectionPool(connectionpool.HTTPConnectionPool):
 
 class UnixAdapter(requests.adapters.HTTPAdapter):
     def __init__(self, base_url, timeout=60):
+        RecentlyUsedContainer = urllib3._collections.RecentlyUsedContainer
         self.base_url = base_url
         self.timeout = timeout
         self.pools = RecentlyUsedContainer(10,