to_file() blows up if prettyprint=False

[tpbradt]

If "prettyprint=False", to_xml_string() converts the xml string to byte instead of string.

File "C:\Python33\Lib\site-packages\junit_xml-1.0-py3.3.egg\junit_xml__init__.py", line 149, in to_file
file_descriptor.write(TestSuite.to_xml_string(test_suites, prettyprint))
TypeError: must be str, not bytes

This is because of the following line in to_xml_string():
xml_string = ET.tostring(xml_element)

which causes ET.tostring() to convert to BytesIO instead of StringIO. The fix is:
xml_string = ET.tostring(xml_element, encoding="unicode")

[brianebeyer]

This must be a Python 2 vs Python 3 issue. I don't know enough about the differences to fix this in a cross-version way. If you have one that works on Python 2 and 3, please send a pull request.

[desolat]

This seems to have been fixed in the meantime as the mentioned line in to_xml_string() uses the given encoding now.