Apparently a UNIQUE index doesn't?

=# \d bit1
                      Table "public.bit1"
     Column     |            Type             |   Modifiers 
---------------+-----------------------------+---------------
  instance_id   | integer                     | not null
  instance_name | character varying(500)      | not null
  created_on    | timestamp without time zone | default now()
  code          | text                        |
  md5sum        | text                        |
  status        | text                        |
  activated_on  | text                        |
  esdnet_uuid   | text                        |
  license       | text                        |
  account_uuid  | text                        | 
Indexes:
     "bit1_instance_id_key" UNIQUE, btree (instance_id)
     "bit1lin_idx" btree (lower(instance_name::text))

Gets reported by slony has having no primary key:

ERROR:  Slony-I: table "public"."bit1" has no primary key

So, just to clarify before I do it, all tables that have 'just a UNIQUE 
key', I'll still have to do 'ALTER TABLE <table> ADD PRIMARY KEY ( field 
);' to so that Slony likes them?