Here is the proof:
Code:
html = soup.serialize_xhtml()
html = html.replace('viewbox', 'viewBox')
html = html.replace('preserveaspectratio', 'preserveAspectRatio')
and everything is fine.
On one hand its fine you found the root cause, on the other hand its a pity it has nothing to with the ignorance of changes sometimes.
I will publish a workaround for this til the new version is out and maybe its a good idea to move the thread to the plugin subforum.