The problem in question turned out to be pilot error, but the error message
from Slony was pretty misleading.

The mistake:
In the slonik script, 2 nodes are defined, but later in the script I attempt
to subscribe a new set to 3 nodes (the 3rd one never existed).

The problem:
Slony reports:
PGRES_FATAL_ERROR select "_sl_schema".subscribeSet(2, 2, 3, 't');  - ERROR:  Slony-I: subscribeSet(): set 2 not found

Set #2 does exist.  The error is that node #3 does not exist.  Took me a
little longer than it should have to discover the actual problem.

This is with slony 1.2.9.  From the release notes, it doesn't look like
1.2.10 has done anything to change this, but I'll try to reproduce it as
soon as I get an opportunity to upgrade.  We're running against Postgres
8.1.

-- 
Bill Moran
Collaborative Fusion Inc.
http://people.collaborativefusion.com/~wmoran/

wmoran at collaborativefusion.com
Phone: 412-422-3463x4023