py3 fixes for admin app

gluon/html.py

@@ -596,17 +596,18 @@ class XML(XmlComponent):
                 for A, IMG and BlockQuote).
                 The key is the tag; the value is a list of allowed attributes.
         """
-
         if sanitize:
             text = sanitizer.sanitize(text, permitted_tags, allowed_attributes)
         if isinstance(text, unicodeT):
             text = to_native(text.encode('utf8', 'xmlcharrefreplace'))
+        elif isinstance(text, bytes):
+            text = to_native(text)
         elif not isinstance(text, str):
             text = str(text)
-        self.text = to_bytes(text)
+        self.text = text
 
     def xml(self):
-        return self.text
+        return to_bytes(self.text)
 
     def __str__(self):
         return self.text