[xml] python 3 testing

[Patrick Welche <prlw1 cam ac uk>]

One change with Python 3 is that all strings are now unicode strings.
I have just been trying to port itstool to Python 3, and see the
following:

Traceback (most recent call last):
  File "../itstool", line 1289, in <module>
    fout.write(doc._doc.serialize('utf-8'))
UnicodeEncodeError: 'ascii' codec can't encode character '\u2192' in position 1027: ordinal not in range(128)

_doc is a libxml2.createFileParserCtxt(filename).doc()


Just calling fout.write(doc._doc.serialize()) instead should to the right
thing? (It gets rid of the error...)

Cheers,

Patrick