Major - P3 If we choose a tombstone to write a disk and the update before it is from the same transaction and with the same timestamp, we skip that update and thus write an older update to the disk. That older value may have already been written to the history store. This triggers the assert:
WT_ASSERT(session, upd_select->upd == NULL || !F_ISSET(upd_select->upd, WT_UPDATE_HS));