UPDATING and DELETING sub-classes

I've tried posting this to pgsql-bugs with no response, so I thought I'd try
here (in case there's something silly I'm doing wrong).

I'm trying to use the DELETE and UPDATE commands to update both the parent
class (which is specfied in the query) and the sub-classes.  According to the
documentation the default behaviour is to include sub-classes and that's
exactly what I want.  Unfortunately it doesn't work:

If I do this:

create table parent ( a int );
create table child ( b int ) inherits (parent);
insert into child values ( 1, 2 );
update parent set a=3 where a=1;

The update does nothing.  I would expect it to update the record in the child
table.

What am I doing wrong?  If this is a bug, is there a workaround?

Thanks,
Ami.