fix ssl_version exception when urllib3 version <= 1.5

docker/ssladapter/ssladapter.py

@@ -2,10 +2,12 @@
       https://lukasa.co.uk/2013/01/Choosing_SSL_Version_In_Requests/
       https://github.com/kennethreitz/requests/pull/799
 """
+from distutils.version import StrictVersion
 from requests.adapters import HTTPAdapter
 try:
     from requests.packages.urllib3.poolmanager import PoolManager
 except ImportError:
+    import urllib3
     from urllib3.poolmanager import PoolManager
 
 
@@ -16,7 +18,13 @@ class SSLAdapter(HTTPAdapter):
         super(SSLAdapter, self).__init__(**kwargs)
 
     def init_poolmanager(self, connections, maxsize, block=False):
-        self.poolmanager = PoolManager(num_pools=connections,
-                                       maxsize=maxsize,
-                                       block=block,
-                                       ssl_version=self.ssl_version)
+        urllib_ver = urllib3.__version__
+        if urllib3 and StrictVersion(urllib_ver) <= StrictVersion('1.5'):
+            self.poolmanager = PoolManager(num_pools=connections,
+                                           maxsize=maxsize,
+                                           block=block)
+        else:
+            self.poolmanager = PoolManager(num_pools=connections,
+                                           maxsize=maxsize,
+                                           block=block,
+                                           ssl_version=self.ssl_version)