In py3k, ElementTree no longer correctly converts characters to entities
when they can't be represented in the requested output encoding.
Python 2:
>>> import xml.etree.ElementTree as ET
>>> e = ET.XML("<?xml version='1.0'
encoding='iso-8859-1'?><body>t\xe3t</body>")
>>> ET.tostring(e, 'ascii')
"<?xml version='1.0' encoding='ascii'?>\n<body>tãt</body>"
Python 3:
>>> import xml.etree.ElementTree as ET
>>> e = ET.XML("<?xml version='1.0'
encoding='iso-8859-1'?><body>t\xe3t</body>")
>>> ET.tostring(e, 'ascii')
.....
UnicodeEncodeError: 'ascii' codec can't encode characters in position
1-2: ordinal not in range(128)
It looks like _encode_entity isn't ever called inside ElementTree
anymore - it probably should be called as part of _encode for characters
that can't be represented.