nodepool - AttributeError: 'Proxy' object has no attribute 'servers'

changes.log

### did the following to get it working again:
# pip3 install --upgrade openstacksdk
# systemctl restart nodepool-launcher

certifi 2018.1.18 -> 2018.11.29
cffi 1.11.5 -> 1.12.1
cryptography 2.2.2 -> 2.5
decorator 4.2.1 -> 4.3.2
dogpile.cache 0.6.5 -> 0.7.1
idna 2.6 -> 2.8
munch 2.2.0 -> 2.3.2
netifaces 0.10.6 -> 0.10.9
openstacksdk 0.23.0 -> 0.24.0
os-service-types 1.2.0 -> 1.5.0
pbr 4.0.1 -> 5.1.2
pycparser 2.18 -> 2.19
PyYAML 3.12 -> 3.13
requests 2.18.4 -> 2.21.0
six 1.11.0 -> 1.12.0
stevedore 1.28.0 -> 1.30.0

nodepool-launcher.log

2019-02-18 14:17:56,757 ERROR nodepool.CleanupWorker: Exception in CleanupWorker (leaked instance cleanup)
Traceback (most recent call last):
  File "/usr/local/lib/python3.5/dist-packages/nodepool/launcher.py", line 643, in _run
    task()
  File "/usr/local/lib/python3.5/dist-packages/nodepool/launcher.py", line 508, in _cleanupLeakedInstances
    manager.cleanupLeakedResources()
  File "/usr/local/lib/python3.5/dist-packages/nodepool/driver/openstack/provider.py", line 478, in cleanupLeakedResources
    for server in self.listNodes():
  File "/usr/local/lib/python3.5/dist-packages/nodepool/driver/openstack/provider.py", line 447, in listNodes
    return self._client.list_servers()
  File "/usr/local/lib/python3.5/dist-packages/openstack/cloud/openstackcloud.py", line 2131, in list_servers
    bare=bare)
  File "/usr/local/lib/python3.5/dist-packages/openstack/cloud/openstackcloud.py", line 2148, in _list_servers
    for server in self.compute.servers(
AttributeError: 'Proxy' object has no attribute 'servers'

pip3-freeze.log

adal==1.2.1
appdirs==1.4.3
asn1crypto==0.24.0
Babel==2.5.3
backcall==0.1.0
bcrypt==3.1.4
blinker==1.3
cachetools==3.0.0
certifi==2018.1.18
cffi==1.11.5
chardet==3.0.4
cloud-init==18.4
command-not-found==0.3
configobj==5.0.6
cryptography==2.2.2
decorator==4.2.1
deprecation==2.0
dictdiffer==0.7.1
diskimage-builder==2.12.1
docutils==0.14
dogpile.cache==0.6.5
extras==1.0.0
flake8==2.5.5
google-auth==1.6.2
idna==2.6
ipython==6.5.0
ipython-genutils==0.2.0
iso8601==0.1.12
jedi==0.12.1
Jinja2==2.8
jmespath==0.9.3
jsonpatch==1.23
jsonpointer==2.0
kazoo==2.4.0
keystoneauth1==3.11.2
kubernetes==8.0.1
language-selector==0.1
lockfile==0.12.2
MarkupSafe==0.23
mccabe==0.4.0
munch==2.2.0
netifaces==0.10.6
networkx==1.11
nodepool==3.4.1.dev16
novaagent==2.1.15
oauthlib==3.0.1
openshift==0.8.4
openstacksdk==0.23.0
os-client-config==1.29.0
os-service-types==1.2.0
packaging==17.1
paramiko==2.4.1
parso==0.3.1
Paste==2.0.3
pbr==4.0.1
pep8==1.7.1
pexpect==4.6.0
pickleshare==0.7.4
prettytable==0.7.2
prompt-toolkit==1.0.15
ptyprocess==0.6.0
pyasn1==0.4.2
pyasn1-modules==0.2.3
pycparser==2.18
pycrypto==2.6.1
pycurl==7.43.0
pyflakes==1.0.0
Pygments==2.2.0
pygobject==3.20.0
PyJWT==1.3.0
PyNaCl==1.2.1
pyparsing==2.2.0
pyserial==3.0.1
python-apt==1.1.0b1+ubuntu0.16.4.2
python-daemon==2.0.6
python-dateutil==2.7.5
python-debian==0.1.27
python-string-utils==0.6.0
python-systemd==231
pytz==2018.3
pyxs==0.4.1
PyYAML==3.12
rackspaceauth==0.8.1
requests==2.18.4
requests-oauthlib==1.2.0
requestsexceptions==1.4.0
rsa==4.0
ruamel.yaml==0.15.87
shade==1.27.1
simplegeneric==0.8.1
six==1.11.0
SQLAlchemy==1.0.19
ssh-import-id==5.5
statsd==3.2.2
stevedore==1.28.0
traitlets==4.3.2
ufw==0.35
unattended-upgrades==0.1
urllib3==1.24.1
virtualenv==15.0.1
voluptuous==0.11.1
wcwidth==0.1.7
WebOb==1.8.2
websocket-client==0.54.0