Issue #18792: Use "127.0.0.1" or "::1" instead of "localhost" as much as possible, since "localhost" goes through a DNS lookup under recent Windows versions.
diff --git a/Lib/test/test_timeout.py b/Lib/test/test_timeout.py
index bfd2a5c..dcf201b 100644
--- a/Lib/test/test_timeout.py
+++ b/Lib/test/test_timeout.py
@@ -110,7 +110,7 @@
     # solution.
     fuzz = 2.0
 
-    localhost = '127.0.0.1'
+    localhost = support.HOST
 
     def setUp(self):
         raise NotImplementedError()