WIP: Futurize false positive.

product/Localizer/MessageCatalog.py

@@ -76,7 +76,7 @@ def to_unicode(x, encoding=None):
     """In Zope the ISO-8859-1 encoding has an special status, normal strings
     are considered to be in this encoding by default.
     """
-    if isinstance(x, str):
+    if isinstance(x, bytes):
         return str(x, encoding or HTTPRequest.default_encoding)
     return str(x)