In rseponse to bug# 1029, force the newline default for StringIO to "\n",

so that even on Windows, after s.write("x\n"), s.getvalue() == "x\n".

Lib/io.py

@@ -1390,7 +1390,7 @@ class StringIO(TextIOWrapper):
 
     # XXX This is really slow, but fully functional
 
-    def __init__(self, initial_value="", encoding="utf-8", newline=None):
+    def __init__(self, initial_value="", encoding="utf-8", newline="\n"):
         super(StringIO, self).__init__(BytesIO(),
                                        encoding=encoding,
                                        newline=newline)