* assume that suffix truncation neither enlarges nor shrinks new high key
      * when applying soft limit, except when last tuple has a posting list.)
      */
 +   Assert(last_truncextra == 0 || isleaf);
     if (pgspc < itupsz + (isleaf ? MAXALIGN(sizeof(ItemPointerData)) : 0) ||
         (pgspc + last_truncextra < state->btps_full && last_off > P_FIRSTKEY))
     {
              ii = PageGetItemId(opage, OffsetNumberPrev(last_off));
             lastleft = (IndexTuple) PageGetItem(opage, ii);
  
 +           Assert(IndexTupleSize(oitup) > last_truncextra);
             truncated = _bt_truncate(wstate->index, lastleft, oitup,
                                      wstate->inskey);
             if (!PageIndexTupleOverwrite(opage, P_HIKEY, (Item) truncated,