[9.16] Fix serve-stale bug when cache has no data
Backport of MR !7856 (merged)
Note that commit 74d30879 is not included in the backport because it changes logging.
Closes #3950 (closed)
Backport of MR !7856 (merged)
Note that commit 74d30879 is not included in the backport because it changes logging.
Closes #3950 (closed)