SF patch #1359365: file and cStringIO raise a ValueError when next() is called
after calling close(). Change StringIO, so that it behaves the same way.
diff --git a/Lib/test/test_StringIO.py b/Lib/test/test_StringIO.py
index c61f7cc..a2e5444 100644
--- a/Lib/test/test_StringIO.py
+++ b/Lib/test/test_StringIO.py
@@ -87,6 +87,8 @@
             eq(line, self._line + '\n')
             i += 1
         eq(i, 5)
+        self._fp.close()
+        self.assertRaises(ValueError, self._fp.next)
 
 class TestStringIO(TestGenericStringIO):
     MODULE = StringIO