One thing I forgot to mention is the progress reporting only updates blocks for the FORK_MAIN. It wouldn't be difficult to report blocks for each fork, but it'd be confusing - the relation counters would remain the same, but the block counters would change for each fork.
I guess we could report the current_relation/fork, but it seems like an overkill. The main fork is by far the largest one, so this seems OK. regards -- Tomas Vondra