The unit test was using the real clock, and depends on ordering by
last-updated timestamps. This means that sometimes two updates both fell
within the granularity of the timestamp in sqlite, which made the
ordering unreliable.
Switching to a mocked clock fixes this, as it moves forward with a hard-
coded pace, regardless of the execution speed of the test.
No functional changes to Flamenco itself.
7db91294c2