The cacheFirst fix in 5511f87 added a yield after fetchAndPopulate
so streams never hang when populate is a no-op for this filter
(the liked-tab spinner-forever bug). Test expectation updated: the
first emission after an empty drift is now the still-empty yield
("we tried, nothing to show yet"), and the simulated drift re-emit
yields the populated rows as the second emission.
bvandeusen
e38189470b