Change some uses of cStringIO.StringIO to io.StringIO.
This is undoubtedly insufficient and in some cases just as broken as before.
diff --git a/Lib/gettext.py b/Lib/gettext.py
index 311e923..a23c2ac 100644
--- a/Lib/gettext.py
+++ b/Lib/gettext.py
@@ -77,10 +77,7 @@
     Python lambda function that implements an equivalent expression.
     """
     # Security check, allow only the "n" identifier
-    try:
-        from cStringIO import StringIO
-    except ImportError:
-        from StringIO import StringIO
+    from io import StringIO
     import token, tokenize
     tokens = tokenize.generate_tokens(StringIO(plural).readline)
     try: