The maintainer today pushed a change where python now explicitly is /usr/bin/python. I haven't tested this change yet but I'd assume this already does the trick. Anyhow, I'd suggest somehow checking ...

File "/mnt/jenkins/workspace/generic-python3-phabricator-pipeline/src/.eggs/ddtrace-0.9.2-py3.5.egg/ddtrace/contrib/pylons/middleware.py", line 58 raise typ, val, tb ...