message: refactor(update-server): Allow vairable test execution times
  This test sometimes fails because we don't catch the writing stage.
  Fundamentally, we're checking that we progress ok to the done stage, so let's
  not fail the test if the asynchronous execution means we miss "writing".
diff: @@ -128,8 +128,7 @@ async def test_update_happypath(test_cli, update_session,
  last_progress = body['progress']
  assert loop.time() - then <= 300
  - assert body['stage'] == 'writing'
  -
  + if body['stage'] == 'writing':
  # Wait through write
  then = loop.time()
  last_progress = 0.0
  