SF patch# 1759016 by Joe Gregorio, who writes:

SF patch# 1759016 by Joe Gregorio, who writes:
1. Removed "returns_unicode" attribute, associated code
   in the module to support that attribute, and all tests
   associated with it.
2. Parsed data is now returned as unicode strings.
3. Changed input tests to use io.BytesIO instead
   of StringIO, to reflect the byte processing
   nature of expat.