I am also seeing this:

tox -e py35 -- --until-failure
py35 develop-inst-noop: /home/michjohn/projects/testactactdeltabug/octavia
py35 installed: /home/michjohn/projects/testactactdeltabug/octavia/.tox/py35/lib/python3.5/site.py:165: DeprecationWarning: 'U' mode is deprecated,  f = open(fullname, "rU"),actdiag==0.5.4,alabaster==0.7.9,alembic==0.8.9,amqp==1.4.9,anyjson==0.3.3,appdirs==1.4.0,automaton==1.6.0,Babel==2.3.4,bandit==1.4.0,beautifulsoup4==4.5.3,blockdiag==1.5.3,cachetools==2.0.0,cffi==1.9.1,chardet==2.3.0,click==6.7,cliff==2.4.0,cmd2==0.6.9,contextlib2==0.5.4,coverage==4.3.2,cryptography==1.7.1,debtcollector==1.10.0,decorator==4.0.11,doc8==0.7.0,docutils==0.12,dulwich==0.16.3,eventlet==0.19.0,extras==1.0.0,fasteners==0.14.1,fixtures==3.0.0,flake8==2.1.0,Flask==0.12,funcparserlib==0.3.6,futurist==0.20.0,gitdb2==2.0.0,GitPython==2.1.1,graphviz==0.5.2,greenlet==0.4.11,gunicorn==19.6.0,hacking==0.9.6,idna==2.2,iso8601==0.1.11,itsdangerous==0.24,Jinja2==2.8.1,jsonpatch==1.15,jsonpointer==1.10,jsonschema==2.5.1,keystoneauth1==2.17.0,keystonemiddleware==4.13.1,kombu==3.0.37,linecache2==1.0.0,logutils==0.3.3,Mako==1.0.6,MarkupSafe==0.23,mccabe==0.2.1,mock==2.0.0,monotonic==1.2,mox3==0.18.0,msgpack-python==0.4.8,netaddr==0.7.19,netifaces==0.10.5,networkx==1.11,nwdiag==1.0.4,-e git+https://github.com/openstack/octavia.git@da1755d610309f15fd5258f07327784b4bb031e1#egg=octavia,olefile==0.44,os-client-config==1.25.0,os-testr==0.8.0,osc-lib==1.3.0,oslo.concurrency==3.17.0,oslo.config==3.21.0,oslo.context==2.11.0,oslo.db==4.16.0,oslo.i18n==3.11.0,oslo.log==3.19.0,oslo.messaging==5.16.0,oslo.middleware==3.22.0,oslo.policy==1.17.0,oslo.reports==1.16.0,oslo.serialization==2.15.0,oslo.service==1.18.0,oslo.utils==3.21.0,oslosphinx==4.9.0,oslotest==2.12.0,paramiko==2.1.1,Paste==2.0.3,PasteDeploy==1.5.2,pbr==1.10.0,pecan==1.2.1,pep8==1.5.6,pika==0.10.0,pika-pool==0.1.3,Pillow==4.0.0,positional==1.1.1,prettytable==0.7.2,psutil==1.2.1,pyasn1==0.1.9,pyasn1-modules==0.0.8,pycadf==2.4.0,pycparser==2.17,pydotplus==2.0.2,pyflakes==0.8.1,Pygments==2.1.3,pyinotify==0.9.6,PyMySQL==0.7.9,pyOpenSSL==16.2.0,pyparsing==2.1.10,pyroute2==0.4.12,python-barbicanclient==4.1.0,python-dateutil==2.6.0,python-editor==1.0.3,python-glanceclient==2.5.0,python-keystoneclient==3.9.0,python-mimeparse==1.6.0,python-neutronclient==6.0.0,python-novaclient==6.0.0,python-subunit==1.2.0,pytz==2016.10,PyYAML==3.12,reno==2.0.3,repoze.lru==0.6,requests==2.12.4,requests-mock==1.2.0,requestsexceptions==1.1.3,restructuredtext-lint==0.17.2,rfc3986==0.4.1,Routes==2.4.1,seqdiag==0.9.5,simplegeneric==0.8.1,simplejson==3.10.0,six==1.10.0,smmap2==2.0.1,snowballstemmer==1.2.1,Sphinx==1.3.6,sphinx-rtd-theme==0.1.9,sphinxcontrib-actdiag==0.8.5,sphinxcontrib-blockdiag==1.5.5,sphinxcontrib-nwdiag==0.9.5,sphinxcontrib-seqdiag==0.8.5,SQLAlchemy==1.0.16,sqlalchemy-migrate==0.10.0,sqlparse==0.2.2,stevedore==1.19.1,taskflow==2.8.0,tempest==14.0.0,Tempita==0.5.2,tenacity==3.7.1,testrepository==0.0.20,testresources==2.0.1,testscenarios==0.5.0,testtools==2.2.0,traceback2==1.4.0,unittest2==1.1.0,urllib3==1.19.1,waitress==1.0.1,warlock==1.2.0,webcolors==1.7,WebOb==1.6.3,WebTest==2.0.24,Werkzeug==0.11.15,wrapt==1.10.8,WSME==0.9.1
py35 runtests: PYTHONHASHSEED='3919688012'
py35 runtests: commands[0] | /home/michjohn/projects/testactactdeltabug/octavia/tools/ostestr_compat_shim.sh --until-failure
/home/michjohn/projects/testactactdeltabug/octavia/.tox/py35/lib/python3.5/site.py:165: DeprecationWarning: 'U' mode is deprecated
  f = open(fullname, "rU")
Traceback (most recent call last):
  File "/home/michjohn/projects/testactactdeltabug/octavia/.tox/py35/bin/ostestr", line 11, in <module>
    sys.exit(main())
  File "/home/michjohn/projects/testactactdeltabug/octavia/.tox/py35/lib/python3.5/site-packages/os_testr/ostestr.py", line 298, in main
    exit(ostestr(sys.argv[1:]))
  File "/home/michjohn/projects/testactactdeltabug/octavia/.tox/py35/lib/python3.5/site-packages/os_testr/ostestr.py", line 294, in ostestr
    return (_select_and_call_runner(opts, regex, others))
  File "/home/michjohn/projects/testactactdeltabug/octavia/.tox/py35/lib/python3.5/site-packages/os_testr/ostestr.py", line 225, in _select_and_call_runner
    opts.until_failure, opts.color, None, others)
  File "/home/michjohn/projects/testactactdeltabug/octavia/.tox/py35/lib/python3.5/site-packages/os_testr/ostestr.py", line 142, in call_testr
    test_list = rb._get_test_list(regex, env)
  File "/home/michjohn/projects/testactactdeltabug/octavia/.tox/py35/lib/python3.5/site-packages/os_testr/regex_builder.py", line 23, in _get_test_list
    stdout=subprocess.PIPE, universal_newlines=True)
  File "/usr/lib/python3.5/subprocess.py", line 947, in __init__
    restore_signals, start_new_session)
  File "/usr/lib/python3.5/subprocess.py", line 1490, in _execute_child
    restore_signals, start_new_session, preexec_fn)
TypeError: Can't convert 'NoneType' object to str implicitly
ERROR: InvocationError: '/home/michjohn/projects/testactactdeltabug/octavia/tools/ostestr_compat_shim.sh --until-failure'