Moved from bitcoin/bitcoin#9464. Low prio, could probably just be closed as wont-fix.

OSX 10.12.2, Qt 5.7.1, master at 2a524b8.

Running with bitcoin-qt -reindex-chainstate, "Number of blocks left" in the modal overlay never updates, and remains as "Unknown. Syncing Headers (446424)...". Even though we've synced > 200'000 blocks.