I think the fix to Christian's issue is just:

Index: Lib/threading.py
===================================================================
--- Lib/threading.py	(révision 79470)
+++ Lib/threading.py	(copie de travail)
@@ -579,7 +579,7 @@
                 try:
                     # We don't call self.__delete() because it also
                     # grabs _active_limbo_lock.
-                    del _active[_get_ident()]
+                    del _active[self.__ident]
                 except:
                     pass
 
@@ -615,7 +615,7 @@
 
         try:
             with _active_limbo_lock:
-                del _active[_get_ident()]
+                del _active[self.__ident]
                 # There must not be any python code between the previous line
                 # and after the lock is released.  Otherwise a tracing function
                 # could try to acquire the lock again in the same thread, (in


Now we just need to add a test for it in test_threading.
And, yes, Amaury's test case looks like a different issue.