check for domain existence before doing any ID work

Bug 1223036

Change-Id: Ie263160b2c75732b13fdbf440b4f2f31ea70d245
Add extra test coverage for unscoped token invalidation

As noted in review https://review.openstack.org/#/c/46972/ - this is
just adding a "missing" one-liner to make the test coverage symmetrical.

Related-Bug: 1226225
Change-Id: I6f008a149cc428fcbb023dd9daa0dae0db53aeac
Merge "check for domain existence before doing any ID work"
Merge "Add extra test coverage for unscoped token invalidation"