Bug with ordering aggregates?

Greetings,

This doesn't seem right to me:

postgres=# select
postgres-# string_agg(column1::text order by column1 asc,',')
postgres-# from (values (3),(4),(1),(2)) a;
string_agg
------------
1234
(1 row)

I'm thinking we should toss a syntax error here and force the 'order
by' to be at the end of any arguments to the aggregate.
Alternatively, we should actually make this work like this one does:

postgres=# select
postgres-# string_agg(column1::text,',' order by column1 asc)
postgres-# from (values (3),(4),(1),(2)) a;
string_agg
------------
1,2,3,4
(1 row)

Thanks,

Stephen