SELECT with join (not only self-join) from archive table may
return incomplete result set, when result set size exceeds
join buffer size.

The problem was that archive row counter was initialzed too
early, when ha_archive::info() method was called. Later,
when optimizer exceeds join buffer, it attempts to reuse
handler without calling ha_archive::info() again (which is
correct).

Fixed by moving row counter initialization from
ha_archive::info() to ha_archive::rnd_init().