Before s_commod() attempts to recursively supply a supply unit it
wants to use as supply source, it zaps the unit's load. When
actually_doit is false, it later restores the old load by overwriting
the change with a saved copy of the unit. That triggers a seqno
mismatch oops.
Avoid that by copying the new sequence number to the saved copy.
(cherry picked from commit
aacd0fb754ef060af92bb08907c5cda196bf34e3)
save = land;
land.lnd_item[type] = 0;
putland(land.lnd_uid, &land);
+ save.lnd_seqno = land.lnd_seqno;
land.lnd_item[type] =
save.lnd_item[type] + s_commod(own, land.lnd_x, land.lnd_y,