Problem creating UNIQUE constraint

Version: 7.0.2

There seems to be a problem with creating a unique constraint, like this:

bray=# CREATE TABLE supplier ( terms      CHAR(2) ,ac_code   CHAR(5)      
UNIQUE)  INHERITS (organisation);
NOTICE:  CREATE TABLE/UNIQUE will create implicit index 'supplier_ac_code_key' 
for table 'supplier'
ERROR:  RelationClearRelation: relation 2951924 modified while in use

but without UNIQUE:

bray=# create table supplier (terms char(2), acs_code char(5)) inherits 
(organisation);
CREATE

bray=# \d organisation           Table "organisation"Attribute  |   Type   |      Modifier      
------------+----------+--------------------ptype      | smallint | id         | char(10) | not nullname       | text
 | not nulladdress    | integer  | salutation | text     | default 'Dear Sir'envelope   | text     | email      | text
  | www        | text     | contact    | char(10) | structure  | char(1)  | department | text     | parent_id  |
char(10)| 
 
Constraints: (((department ISNULL) AND (parent_id ISNULL)) OR ((department > 
''::text) AND (parent_id > ''::bpchar)))            ((((structure = 'L'::bpchar) OR (structure = 'C'::bpchar)) OR 
(structure = 'U'::bpchar)) OR (structure = 'O'::bpchar))
Rules: organisation_type_ins_rule,      organisation_type_upd_rule
Triggers: RI_ConstraintTrigger_2950794,         RI_ConstraintTrigger_2950240

bray=# 

-- 
Oliver Elphick                                Oliver.Elphick@lfix.co.uk
Isle of Wight                              http://www.lfix.co.uk/oliver
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