Description of problem:
There was an issue discovered upstream while running Rally tests that showed that the list method for API versions <= 2.34 would fail if no search options were specified for the list command. This would cause the Manila Client to attempt to pop from a NoneType object causing a stack trace.

Version-Release number of selected component (if applicable):
python-manilaclient-1.17.1-0.20170814140937.502eb75.el7ost.noarch

How reproducible:
Seems to always be reproducible with upstream Rally tests.

Steps to Reproduce:
1. Deploy OSP-12 and ensure that Manila is installed.
2. Configure and run the Rally tests for Manila. 
3. Observe that the list method fails when no search options are specified as parameters to the list method.

Actual results:
Traceback (most recent call last):
  File "/opt/stack/new/rally/rally/task/runner.py", line 72, in _run_scenario_once
    getattr(scenario_inst, method_name)(**scenario_kwargs)
  File "/opt/stack/new/rally/rally/plugins/openstack/scenarios/manila/shares.py", line 325, in run
    self._list_shares(detailed=detailed)
  File "/opt/stack/new/rally/rally/task/atomic.py", line 86, in func_atomic_actions
    f = func(self, *args, **kwargs)
  File "/opt/stack/new/rally/rally/plugins/openstack/scenarios/manila/utils.py", line 99, in _list_shares
    detailed=detailed, search_opts=search_opts)
  File "/opt/stack/new/python-manilaclient/manilaclient/api_versions.py", line 399, in substitution
    return method.func(obj, *args, **kwargs)
  File "/opt/stack/new/python-manilaclient/manilaclient/v2/shares.py", line 328, in list
    search_opts.pop("export_location", None)
AttributeError: 'NoneType' object has no attribute 'pop'

Expected results:
Rally Tests shall pass successfully.

Additional info:
It looks like this issue was fixed upstream already by https://review.openstack.org/#/c/488848/1. Should be fairly easy to pull this down and put it into our packages.