diff -r f9b4cfc19264 Lib/test/test_marshal.py
--- a/Lib/test/test_marshal.py	Sat Jun 18 19:34:12 2011 -0400
+++ b/Lib/test/test_marshal.py	Sun Jun 26 10:19:55 2011 +0200
@@ -211,6 +211,42 @@
         invalid_string = b'l\x02\x00\x00\x00\x00\x00\x00\x00'
         self.assertRaises(ValueError, marshal.loads, invalid_string)
 
+class MultipleTestCase(unittest.TestCase):
+    """
+    http://bugs.python.org/issue12291 file written using marshal in 3.2 can be read by 2.7, but not 3.2 or 3.3
+
+    actually files written 3.x can not be read on 3.x.
+    """
+
+    def test_multiple_dump_reload(self):
+        data = ( 1, 'abc', 1.0 )
+        pos = []
+        try:
+            with open(support.TESTFN, "wb") as f:
+                for d in data:
+                    marshal.dump(d, f)
+                    pos.append(f.tell())
+            with open(support.TESTFN, "rb") as f:
+                for i in range(len(data)):
+                    self.assertEqual(data[i], marshal.load(f))
+                    self.assertEqual(pos[i], f.tell())
+        finally:
+            support.unlink(support.TESTFN)
+
+    def test_multiple_dump_reload_interleaved(self):
+        data = ( 1, 'abc', 1.0 )
+        pos = []
+        with open(support.TESTFN, "wb") as f:
+            for d in data:
+                marshal.dump(d, f)
+                f.write(bytes("0123", "ascii"))
+                pos.append(f.tell())
+        with open(support.TESTFN, "rb") as f:
+            for i in range(len(data)):
+                self.assertEqual(data[i], marshal.load(f))
+                f.read(4)
+                self.assertEqual(pos[i], f.tell())
+        os.unlink(support.TESTFN)
 
 def test_main():
     support.run_unittest(IntTestCase,
@@ -219,7 +255,8 @@
                               CodeTestCase,
                               ContainerTestCase,
                               ExceptionTestCase,
-                              BugsTestCase)
+                              BugsTestCase,
+                              MultipleTestCase)
 
 if __name__ == "__main__":
     test_main()