In svn HEAD (r90), on line 22 of patch.py, StringIO is imported using "from
StringIO import StringIO". But on line 70 (in fromstring()), the code tries to
instantiate "StringIO.StringIO", which fails with an AttributeError.
This can be fixed by either changing the import to just "import StringIO" or by
removing the initial "StringIO." from the place where StringIO is instantiated.