backslash replaced by null character

Hello,

I have following snipped:

from docutils.core import publish_doctree
dom = publish_doctree(r'Foo\\bar').asdom()
print(repr(dom.toxml()))

with docutils>=0.16, I get:
u'<?xml version="1.0" ?><document
source="&lt;string&gt;"><paragraph>Foo\x00\\bar</paragraph></document>'

with previous versions I get:
u'<?xml version="1.0" ?><document
source="&lt;string&gt;"><paragraph>Foo\\bar</paragraph></document>'

Why with the newest docutils versions I'm getting \x00 in the output?