Revert "Ensure connections are properly closed on object destruction" (…

…#291)

This reverts commit 1922dda.

Fixes #292.

urllib3/_collections.py

@@ -51,9 +51,6 @@ def __init__(self, maxsize=10, dispose_func=None):
         self._container = self.ContainerCls()
         self.lock = RLock()
 
-    def __del__(self):
-        self.clear()
-
     def __getitem__(self, key):
         # Re-insert the item, moving it to the end of the eviction line.
         with self.lock:

urllib3/connectionpool.py

@@ -167,9 +167,6 @@ def __init__(self, host, port=None, strict=False,
         self.num_connections = 0
         self.num_requests = 0
 
-    def __del__(self):
-        self.close()
-
     def _new_conn(self):
         """
         Return a fresh :class:`httplib.HTTPConnection`.

urllib3/poolmanager.py

@@ -68,9 +68,6 @@ def __init__(self, num_pools=10, headers=None, **connection_pool_kw):
         self.pools = RecentlyUsedContainer(num_pools,
                                            dispose_func=lambda p: p.close())
 
-    def __del__(self):
-        self.clear()
-
     def _new_pool(self, scheme, host, port):
         """
         Create a new :class:`ConnectionPool` based on host, port and scheme.