Tests are failing for current master branch (16th of May, 2017)

After pretty recent upgrade of oslo.config there are failing tests in python-glance-store: please, see attached file for detailed log.

```
root@e759a62b90ba:/build/glance_store# tox -ve py27,pep8
using tox.ini: /build/glance_store/tox.ini
using tox-2.3.1 from /usr/lib/python3/dist-packages/tox/__init__.py
py27 create: /build/glance_store/.tox/py27
  /build/glance_store/.tox$ /usr/bin/python3 -m virtualenv --python /usr/bin/python2.7 py27 >/build/glance_store/.tox/py27/log/py27-0.log
py27 installdeps: -r/build/glance_store/requirements.txt, -r/build/glance_store/test-requirements.txt, .[vmware,swift,cinder]
  /build/glance_store$ /build/glance_store/tools/tox_install.sh https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt --allow-all-external --allow-insecure netaddr -U -r/build/glance_store/requirements.txt -r/build/glance_store/test-requirements.txt .[vmware,swift,cinder] >/build/glance_store/.tox/py27/log/py27-1.log
py27 develop-inst: /build/glance_store
  /build/glance_store$ /build/glance_store/tools/tox_install.sh https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt --allow-all-external --allow-insecure netaddr -U -e /build/glance_store >/build/glance_store/.tox/py27/log/py27-2.log
  /build/glance_store$ /build/glance_store/.tox/py27/bin/pip freeze >/build/glance_store/.tox/py27/log/py27-3.log
py27 installed: alabaster==0.7.10,appdirs==1.4.3,Babel==2.3.4,bandit==1.4.0,cffi==1.10.0,coverage==4.4.1,debtcollector==1.13.0,docutils==0.13.1,dulwich==0.17.3,enum-compat==0.0.2,enum34==1.1.6,eventlet==0.20.1,extras==1.0.0,fasteners==0.14.1,fixtures==3.0.0,flake8==2.5.5,funcsigs==1.0.2,functools32==3.2.3.post2,futures==3.1.1,gitdb2==2.0.0,GitPython==2.1.3,-e git+https://github.com/openstack/glance_store.git@a783a7442b6034d22773410bf296ee3952c9d51a#egg=glance_store,greenlet==0.4.12,hacking==0.12.0,httplib2==0.10.3,imagesize==0.7.1,iso8601==0.1.11,Jinja2==2.9.6,jsonschema==2.6.0,keystoneauth1==2.20.0,linecache2==1.0.0,lxml==3.7.3,MarkupSafe==1.0,mccabe==0.2.1,mock==2.0.0,monotonic==1.3,mox3==0.21.0,msgpack-python==0.4.8,netaddr==0.7.19,netifaces==0.10.5,-e git+https://git.openstack.org/openstack/requirements@1e7ed0d383df230435e5ea990a212c72041caf4f#egg=openstack_requirements,os-brick==1.12.0,os-client-config==1.27.0,os-testr==0.8.1,os-win==2.0.1,oslo.concurrency==3.20.0,oslo.config==4.1.1,oslo.context==2.13.0,oslo.i18n==3.15.1,oslo.log==3.26.1,oslo.privsep==1.19.0,oslo.rootwrap==5.7.0,oslo.serialization==2.18.0,oslo.service==1.23.0,oslo.utils==3.25.1,oslo.vmware==2.19.0,oslosphinx==4.12.0,oslotest==2.15.0,packaging==16.8,Parsley==1.3,Paste==2.0.3,PasteDeploy==1.5.2,pbr==3.0.0,pep8==1.5.7,pkg-resources==0.0.0,positional==1.1.1,prettytable==0.7.2,pycparser==2.17,pyflakes==0.8.1,Pygments==2.2.0,pyinotify==0.9.6,pyparsing==2.2.0,python-cinderclient==2.0.1,python-dateutil==2.6.0,python-keystoneclient==3.10.0,python-mimeparse==1.6.0,python-subunit==1.2.0,python-swiftclient==3.3.0,pytz==2017.2,PyYAML==3.12,reno==2.2.1,repoze.lru==0.6,requests==2.14.2,requests-mock==1.3.0,requestsexceptions==1.2.0,retrying==1.3.3,rfc3986==1.0.0,Routes==2.4.1,simplejson==3.10.0,six==1.10.0,smmap2==2.0.1,snowballstemmer==1.2.1,Sphinx==1.5.6,stevedore==1.21.0,suds-jurko==0.6,testrepository==0.0.20,testscenarios==0.5.0,testtools==2.3.0,traceback2==1.4.0,unittest2==1.1.0,urllib3==1.21.1,WebOb==1.7.2,wrapt==1.10.10
py27 runtests: PYTHONHASHSEED='3977214195'
py27 runtests: commands[0] | ostestr --slowest

...

======
Totals
======
Ran: 331 tests in 4.0000 sec.
 - Passed: 286
 - Skipped: 0
 - Expected Fail: 0
 - Unexpected Success: 0
 - Failed: 45
Sum of execute time for each test: 4.6771 sec.

==============
Worker Balance
==============
 - Worker 0 (83 tests) => 0:00:01.464240
 - Worker 1 (83 tests) => 0:00:01.494265
 - Worker 2 (83 tests) => 0:00:01.500238
 - Worker 3 (82 tests) => 0:00:01.335776

Slowest Tests:

...

pep8 create: /build/glance_store/.tox/pep8
  /build/glance_store/.tox$ /usr/bin/python3 -m virtualenv --python /usr/bin/python3 pep8 >/build/glance_store/.tox/pep8/log/pep8-0.log
pep8 installdeps: -r/build/glance_store/requirements.txt, -r/build/glance_store/test-requirements.txt, .[vmware,swift,cinder]
  /build/glance_store$ /build/glance_store/tools/tox_install.sh https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt --allow-all-external --allow-insecure netaddr -U -r/build/glance_store/requirements.txt -r/build/glance_store/test-requirements.txt .[vmware,swift,cinder] >/build/glance_store/.tox/pep8/log/pep8-1.log
pep8 develop-inst: /build/glance_store
  /build/glance_store$ /build/glance_store/tools/tox_install.sh https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt --allow-all-external --allow-insecure netaddr -U -e /build/glance_store >/build/glance_store/.tox/pep8/log/pep8-2.log
  /build/glance_store$ /build/glance_store/.tox/pep8/bin/pip freeze >/build/glance_store/.tox/pep8/log/pep8-3.log
pep8 installed: alabaster==0.7.10,appdirs==1.4.3,Babel==2.3.4,bandit==1.4.0,cffi==1.10.0,coverage==4.4.1,debtcollector==1.13.0,docutils==0.13.1,dulwich==0.17.3,enum-compat==0.0.2,eventlet==0.20.1,extras==1.0.0,fasteners==0.14.1,fixtures==3.0.0,flake8==2.5.5,gitdb2==2.0.0,GitPython==2.1.3,-e git+https://github.com/openstack/glance_store.git@a783a7442b6034d22773410bf296ee3952c9d51a#egg=glance_store,greenlet==0.4.12,hacking==0.12.0,httplib2==0.10.3,imagesize==0.7.1,iso8601==0.1.11,Jinja2==2.9.6,jsonschema==2.6.0,keystoneauth1==2.20.0,linecache2==1.0.0,lxml==3.7.3,MarkupSafe==1.0,mccabe==0.2.1,mock==2.0.0,monotonic==1.3,mox3==0.21.0,msgpack-python==0.4.8,netaddr==0.7.19,netifaces==0.10.5,-e git+https://git.openstack.org/openstack/requirements@1e7ed0d383df230435e5ea990a212c72041caf4f#egg=openstack_requirements,os-brick==1.12.0,os-client-config==1.27.0,os-testr==0.8.1,os-win==2.0.1,oslo.concurrency==3.20.0,oslo.config==4.1.1,oslo.context==2.13.0,oslo.i18n==3.15.1,oslo.log==3.26.1,oslo.privsep==1.19.0,oslo.rootwrap==5.7.0,oslo.serialization==2.18.0,oslo.service==1.23.0,oslo.utils==3.25.1,oslo.vmware==2.19.0,oslosphinx==4.12.0,oslotest==2.15.0,packaging==16.8,Parsley==1.3,Paste==2.0.3,PasteDeploy==1.5.2,pbr==3.0.0,pep8==1.5.7,pkg-resources==0.0.0,positional==1.1.1,prettytable==0.7.2,pycparser==2.17,pyflakes==0.8.1,Pygments==2.2.0,pyinotify==0.9.6,pyparsing==2.2.0,python-cinderclient==2.0.1,python-dateutil==2.6.0,python-keystoneclient==3.10.0,python-mimeparse==1.6.0,python-subunit==1.2.0,python-swiftclient==3.3.0,pytz==2017.2,PyYAML==3.12,reno==2.2.1,repoze.lru==0.6,requests==2.14.2,requests-mock==1.3.0,requestsexceptions==1.2.0,retrying==1.3.3,rfc3986==1.0.0,Routes==2.4.1,simplejson==3.10.0,six==1.10.0,smmap2==2.0.1,snowballstemmer==1.2.1,Sphinx==1.5.6,stevedore==1.21.0,suds-jurko==0.6,testrepository==0.0.20,testscenarios==0.5.0,testtools==2.3.0,traceback2==1.4.0,unittest2==1.1.0,urllib3==1.21.1,WebOb==1.7.2,wrapt==1.10.10
pep8 runtests: PYTHONHASHSEED='3977214195'
pep8 runtests: commands[0] | flake8
  /build/glance_store$ /build/glance_store/.tox/pep8/bin/flake8
pep8 runtests: commands[1] | bandit -r glance_store -x tests --skip B101,B110,B303
  /build/glance_store$ /build/glance_store/.tox/pep8/bin/bandit -r glance_store -x tests --skip B101,B110,B303
[main] INFO profile include tests: None
[main] INFO profile exclude tests: None
[main] INFO cli include tests: None
[main] INFO cli exclude tests: B101,B110,B303
[main] INFO running on Python 3.5.2
Run started:2017-05-16 14:49:06.287301

Test results:
 No issues identified.

Code scanned:
 Total lines of code: 5241
 Total lines skipped (#nosec): 0

Run metrics:
 Total issues (by severity):
  Undefined: 0.0
  Low: 0.0
  Medium: 0.0
  High: 0.0
 Total issues (by confidence):
  Undefined: 0.0
  Low: 0.0
  Medium: 0.0
  High: 0.0
Files skipped (0):
______________________________________________________ summary ______________________________________________________
ERROR: py27: commands failed
  pep8: commands succeeded
```