portal_transform result should be str, not unicode.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@41876 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/PortalTransforms/transforms/xml_to_text.py

@@ -14,7 +14,7 @@ class xml_to_text:
 
     def convert(self, data, cache, **kw):
         text_list = etree.fromstring(data).itertext()
-        out = ' '.join([text for text in text_list if text])
+        out = ' '.join([text for text in text_list if text]).encode('utf-8')
         cache.setData(out)
         return cache