Drop the max stack depth to something that works in 2.6
diff --git a/Python/marshal.c b/Python/marshal.c
index 8faea47..eac4616 100644
--- a/Python/marshal.c
+++ b/Python/marshal.c
@@ -15,7 +15,7 @@
  * and risks coring the interpreter.  When the object stack gets this deep,
  * raise an exception instead of continuing.
  */
-#define MAX_MARSHAL_STACK_DEPTH 5000
+#define MAX_MARSHAL_STACK_DEPTH 2000
 
 #define TYPE_NULL		'0'
 #define TYPE_NONE		'N'