The monkey patch for urllib.request._urlopener does nothing on Python 3.

(cherry picked from commit f1589378)

src/zc/buildout/download.py

@@ -20,25 +20,8 @@ except ImportError:
 
 try:
     # Python 3
-    from urllib.request import FancyURLopener, URLopener, urlretrieve
+    from urllib.request import urlretrieve
     from urllib.parse import urlparse
-    from urllib import request
-    import warnings
-
-    class PatchedURLopener(FancyURLopener):
-        http_error_default = URLopener.http_error_default
-
-        def __init__(self, *args, **kwargs):
-            with warnings.catch_warnings():
-                warnings.simplefilter('ignore')
-                # This creates a DeprecationWarning on 3.6:
-                # PatchedURLopener style of invoking requests is deprecated.
-                # Use newer urlopen functions/methods.
-                # Said warning breaks our doctests.
-                super(PatchedURLopener, self).__init__(*args, **kwargs)
-
-    request._urlopener = PatchedURLopener()  # Ook! Monkey patch!
-
 except ImportError:
     # Python 2
     import base64