defusedxml is not really compatible with Python 3.6. There was a significant change upstream in how `xml.etree.ElementTree.iterparse` is implemented, and defusedxml simply cannot cope with that. A partial fix has been committed upstream, but the relevant code still doesn't actually work properly. I have filed an upstream issue for this: https://github.com/tiran/defusedxml/issues/3 I ran into this while trying to rebuild python-fedmsg-meta-fedora-infrastructure ; there's a dep chain which runs: python-fedmsg-meta-fedora-infrastructure python-fedora python3-openid python-defusedxml and defusedxml fails. So as well as fedmsg-meta, openid and fedora and anything else that uses those is broken till this can be fixed.
Thanks for the upstream issue. In the rebuilding rush I haven't noticed one of the packages that fail is mine.
I also reported to python.org, on the basis that the docs for 'xml' explicitly endorse the use of 'defusedxml': https://bugs.python.org/issue29050
Well, with the benefit of a bit of sleep and coffee and some insights from puiterwijk, I came up with (I think) a proper fix for this, and sent it upstream: https://github.com/tiran/defusedxml/pull/4 https://koji.fedoraproject.org/koji/taskinfo?taskID=17031413