Index: Lib/test/crashers/gc_inspection.py
===================================================================
--- Lib/test/crashers/gc_inspection.py	(revision 47245)
+++ Lib/test/crashers/gc_inspection.py	(working copy)
@@ -1,17 +1,68 @@
 """
 gc.get_referrers() can be used to see objects before they are fully built.
+
+The problem stems from pre-allocating a tuple, then filling it by calling
+user-defined code. Once the user has control again, gc.get_referrers() can
+be used to grab the pre-allocated tuple; all you have to do then is try to
+use an unfilled tuple index to crash the interpreter.
+
+The following test cases indicate places where this behaviour has been found.
 """
 
 import gc
+import os
 
+def test_tuple():
+    def g():
+        marker = object()
+        yield marker
+        # now the marker is in the tuple being constructed
+        referrers = [x for x in gc.get_referrers(marker) if type(x) is tuple]
+        if referrers:
+            print referrers[0]
+            print referrers[0][1]
 
-def g():
-    marker = object()
-    yield marker
-    # now the marker is in the tuple being constructed
-    [tup] = [x for x in gc.get_referrers(marker) if type(x) is tuple]
-    print tup
-    print tup[1]
+    tuple(g())
+    
+def test_filter():
+    """
+    Bug report: python.org/sf/1517663
+    """
+    class BadSeq(tuple):
+        def __getitem__(self, index):
+            if index == 0:
+                self.marker = object()
+                return self.marker
 
+            referrers = [x for x in gc.get_referrers(self.marker) if type(x) is tuple]
+            if referrers:
+                print referrers[0]
+                print referrers[0][1]
 
-tuple(g())
+    filter(None, BadSeq([5, 6, 7, 9, 10]))
+
+results = []
+for test_func in [test_tuple, test_filter]:
+    print "### Starting", test_func.__name__
+    print "#################################"
+    
+    child_id = os.fork()
+    if child_id:
+        (pid, status) = os.waitpid(child_id, 0)
+        
+        if status:
+            results.append(test_func.__name__ + " failed")
+        else:
+            results.append(test_func.__name__ + " passed")
+            
+        # Add some whitespace to make things legible
+        print
+        print
+    else:
+        test_func()
+        print test_func.__name__, "passed"
+        raise SystemExit()
+
+for res in results:
+    print res
+