The mutex module has been deprecated for removal in 3.0.
diff --git a/Lib/mutex.py b/Lib/mutex.py
index 5d35bdf..9e6b8d4 100644
--- a/Lib/mutex.py
+++ b/Lib/mutex.py
@@ -11,6 +11,9 @@
 Of course, no multi-threading is implied -- hence the funny interface
 for lock, where a function is called once the lock is aquired.
 """
+from warnings import warnpy3k
+warnpy3k("the mutex module has been removed in Python 3.0", stacklevel=2)
+del warnpy3k
 
 from collections import deque