Updated openstack/openstack
Project: openstack/keystone  bd63b9e82c3ca7b814f0120f8d383fe6cd39f308

use expected_length parameter to assert expected length

assertValidRoleAssignmentListResponse method provides expected_length
parameter to assert expected length of list response. However, we
do not use it.

Change-Id: Ifc9ff3f13809ef939d2154d1ddd8648735efb613