ZoL update:
Author: Tom Caputi <tcaputi@datto.com>
Date:   Wed May 1 20:34:24 2019 -0400

    Fix estimated scrub completion time

        Currently, it is possible for the 'zpool scrub' command to
        progress slightly beyond 100% due to concurrent changes
        happening on the live pool. This behavior is expected, but
        the userspace code for 'zpool status' would subtract the
        expected amount of data from the amount of data already
        scrubbed, resulting in a negative integer being casted to a
        large positive one. This number was then used to calculate
        the estimated completion time, resulting in wildly wrong
        results. This code changes the behavior so that 'zpool status'
        does not attempt to report an estimate during this period.

        Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
        Reviewed-by: Igor Kozhukhov <igor@dilos.org>
        Reviewed-by: George Melikov <mail@gmelikov.ru>
        Signed-off-by: Tom Caputi <tcaputi@datto.com>
        Closes #8611
        Closes #8687
After this fix, the zpool status output does display more reasonable output.