Fix bug in marshal where bad data would cause a segfault due to
lack of an infinite recursion check.

Contributed by Damien Miller at Google.
diff --git a/Misc/NEWS b/Misc/NEWS
index 8e8254d..67c4750 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,9 @@
 Library
 -------
 
+- Fix bug in marshal where bad data would cause a segfault due to
+  lack of an infinite recursion check.
+
 - HTML-escape the plain traceback in cgitb's HTML output, to prevent
   the traceback inadvertently or maliciously closing the comment and
   injecting HTML into the error page.