Fix misleading hash invalidations test comments
Fix misleading hash invalidations test comments

...and refactor two extremely similar tests to use a single
helper method - the only paramerization being the existence
or not of hashes.pkl at start of the test.

Change-Id: I601218a9a031e7fc77bc53ea735e89700ec1647d
Related-Change: Ia43ec2cf7ab715ec37f0044625a10aeb6420f6e3

openstack/swift,openstack/swift,matthewoliver/swift,smerritt/swift,swiftstack/swift,clayg/swift,notmyname/swift,swiftstack/swift,notmyname/swift,tipabu/swift,openstack/swift,redbo/swift,tipabu/swift,clayg/swift,clayg/swift,psachin/swift,nadeemsyed/swift,psachin/swift,psachin/swift,matthewoliver/swift,nadeemsyed/swift,tipabu/swift,swiftstack/swift,smerritt/swift,notmyname/swift,clayg/swift,smerritt/swift,matthewoliver/swift,openstack/swift,nadeemsyed/swift,redbo/swift,notmyname/swift,smerritt/swift,matthewoliver/swift,psachin/swift,nadeemsyed/swift,tipabu/swift