Related change is If5d00a7f7991d78243e76a6e22031c185caee80a
Add new action in tests.v1.fakes.FakeHTTPClient, so it allow to test
os-begin_detaching and os-roll_detaching.
Fix typo in tests/v1/test_volumes.py.
Change-Id: I5c4cd9cc56a7235036b6bab6641554b5919ffbb6