Issue #11500: Fixed a bug in the os x proxy bypass code for fully qualified
IP addresses in the proxy exception list.
diff --git a/Lib/urllib.py b/Lib/urllib.py
index 1553f9d..84e9dbc 100644
--- a/Lib/urllib.py
+++ b/Lib/urllib.py
@@ -1396,7 +1396,7 @@
 
                 else:
                     mask = int(mask[1:])
-                    mask = 32 - mask
+                mask = 32 - mask
 
                 if (hostIP >> mask) == (base >> mask):
                     return True