Rescan progress notifications may be handled after rescan finishes.

[jrick]

Because rescan notifications are "buffered" with the rest of notification processing (especially with recvtx and redeemingtx), they may be handled by the rescan manager after a rescan has finished (after the rescan RPC returns). There needs to be some synchronization between these notifications for the rescan manager so that progress notifications are not handled before the rescan finished notification, and so wallets will not be marked partially synced even after a rescan completed successfully.

[jrick]

A large part of this issue is how btcd processes notifications. Notifications are queued up and sent asynchronously from the code which created the notifiation, which means there is no guarantee that a rescanprogress notification will be sent before the rescan RPC returns.

The best and easiest solution here would probably be to signal a finished rescan from a new notification, rather than based on the rescan RPC returning.