Why is harfbuzz package did not get pick for f30 mass-rebuild?
Mass rebuild script has an epoch time, anything that's built after the epoch has already been built with the requirements for the mass rebuild so it's not attempted again. The epoch for F-30 was '2019-01-31 10:10:00.000000' and you built harfbuzz-2.3.1-1.fc30 after the epoch so there was no need to rebuild it.
Metadata Update from @pbrobinson: - Issue close_status updated to: It's all good - Issue status updated to: Closed (was: Open)