> the FAILOVER slonik command ran with error?
yes.

Setup:

Node #1 
  - origin of set 2
  - nobody else subscribed to set 2
  - machine dead, cant use slonik command like drop set
Node #2
  - Subscribed to set 1
Node #3 
  - Origin of set 1

logs are not beeing deleted now because node #1 is still in cluster.
I can not use failover because nobody else subsribed to set 2
I can not use drop node because node 1 is origin of set 2

%slonik drop2.slonik
drop2.slonik:8: PGRES_FATAL_ERROR select "_com".dropNode(1);  - ERROR:  Slony-I: Node 1 is still origin of one or more sets
%cat drop2.slonik
CLUSTER NAME = com;
drop node (id = 1, event node = 2);

i think this is bug in drop node command. if nobody else is subscribed to
set originating at dead mode, it should allow to drop that node.