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/quopri.py b/Lib/quopri.py
index fccfe85..5002cc8 100755
--- a/Lib/quopri.py
+++ b/Lib/quopri.py
@@ -105,7 +105,7 @@
 def encodestring(s, quotetabs = 0, header = 0):
     if b2a_qp is not None:
         return b2a_qp(s, quotetabs = quotetabs, header = header)
-    from cStringIO import StringIO
+    from io import StringIO
     infp = StringIO(s)
     outfp = StringIO()
     encode(infp, outfp, quotetabs, header)
@@ -159,7 +159,7 @@
 def decodestring(s, header = 0):
     if a2b_qp is not None:
         return a2b_qp(s, header = header)
-    from cStringIO import StringIO
+    from io import StringIO
     infp = StringIO(s)
     outfp = StringIO()
     decode(infp, outfp, header = header)