Quoting Glyn Astill <glynastill at yahoo.co.uk>:
> --- On Mon, 19/10/09, Glyn Astill <glynastill at yahoo.co.uk> wrote:
>> Hi chaps,
>>
>> Is anyone else seeing this when doing UPGRADE
>> FUNCTIONS?  I'm guessing it's the recent int / bigint
>> changes?
>>
>> And I'm getting:
>>
>> glyn at Way5d:/pgsql/slony$ slonik upgrade_functions.scr
>> upgrade_functions.scr:9: Possible unsupported PostgreSQL
>> version 8.3, defaulting to 8.1 support
>> upgrade_functions.scr:9: loading of file
>> /usr/local/pgsql/share//slony1_funcs.sql: PGRES_FATAL_ERROR
>> ERROR:  cannot change return type of existing function
>> HINT:  Use DROP FUNCTION first.
>> ERROR:  cannot change return type of existing
>> function
>> HINT:  Use DROP FUNCTION first.
>
>
> I bumbled around it with the following on each node:
>
> psql -U slony -d SEE -c 'drop function  
> _main_replication_test.ddlscript_complete(integer, text, integer)'
> psql -U slony -d SEE -c 'drop function  
> _main_replication_test.updatereloid(integer, integer)'
> sed -e  
> 's/@NAMESPACE@/_main_replication_test/g;s/@MODULEVERSION@/1.2.17/g'  
> slony1_funcs.sql | psql -U slony -d SEE

The following patch should rectify this...

Index: slony1_funcs.sql
===================================================================
RCS file: /home/cvsd/slony1/slony1-engine/src/backend/slony1_funcs.sql,v
retrieving revision 1.145.2.19
diff -c -u -r1.145.2.19 slony1_funcs.sql
cvs diff: conflicting specifications of output style
--- slony1_funcs.sql    23 Sep 2009 16:14:32 -0000      1.145.2.19
+++ slony1_funcs.sql    21 Oct 2009 12:32:57 -0000
@@ -3643,6 +3643,8 @@
  --
  --     Generate the DDL_SCRIPT event
  -- ----------------------------------------------------------------------
+drop function if exists @NAMESPACE at .ddlScript_complete (int4, text,  
int4);  -- Needed because function signature has changed!
+
  create or replace function @NAMESPACE at .ddlScript_complete (int4, text, int4)
  returns bigint
  as $$
@@ -5063,6 +5065,7 @@
  --
  --      Reset the relnames
  -- ----------------------------------------------------------------------
+drop function if exists @NAMESPACE at .updateReloid (int4, int4);
  create or replace function @NAMESPACE at .updateReloid (int4, int4)
  returns bigint
  as $$

That's working and committed to 2.0 + HEAD.