master branch requires 0.6.2 of dogpile.cache

[James Page]

Detected in branch package builds in Ubuntu:

${PYTHON:-python} -m subunit.run discover -t ./ ${OS_TEST_PATH:-./keystone/tests/unit} --list
--- import errors ---
Failed to import test module: keystone.tests.unit
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/unittest2/loader.py", line 490, in _find_test_path
    package = self._get_module_from_name(name)
  File "/usr/lib/python2.7/dist-packages/unittest2/loader.py", line 395, in _get_module_from_name
    __import__(name)
  File "keystone/tests/unit/__init__.py", line 24, in <module>
    from keystone.tests.unit.core import * # noqa
  File "keystone/tests/unit/core.py", line 46, in <module>
    from keystone.common import request
  File "keystone/common/request.py", line 18, in <module>
    from keystone.common import authorization
  File "keystone/common/authorization.py", line 23, in <module>
    from keystone.models import token_model
  File "keystone/models/token_model.py", line 22, in <module>
    from keystone.federation import constants
  File "keystone/federation/__init__.py", line 15, in <module>
    from keystone.federation.core import * # noqa
  File "keystone/federation/core.py", line 17, in <module>
    from keystone.common import cache
  File "keystone/common/cache/__init__.py", line 15, in <module>
    from keystone.common.cache.core import * # noqa
  File "keystone/common/cache/core.py", line 56, in <module>
    class DistributedInvalidationStrategy(region.RegionInvalidationStrategy):
AttributeError: 'module' object has no attribute 'RegionInvalidationStrategy'

RegionInvalidationStrategy was introduced in 0.6.2, however the minimum requirement in global-requirements is currently 0.6.1.

Upstream release notes: https://dogpilecache.readthedocs.io/en/latest/changelog.html#change-0.6.2

[Steve Martinelli (stevemar)]

This should be resolved by https://review.openstack.org/#/c/362795/ and https://review.openstack.org/#/c/362928/

[Steve Martinelli (stevemar)]

the two patches are merged now, dogpile 0.6.2 is now the minimum version