BUG #5676: When creating a trigger an dummy argument is inserted.

The following bug has been logged online:

Bug reference: 5676
Logged by: Christopher Hotchkiss
Email address: christopher(dot)a(dot)hotchkiss(at)jpmchase(dot)com
PostgreSQL version: 9.0.0
Operating system: Ubuntu 10.04 x64
Description: When creating a trigger an dummy argument is inserted.
Details:

When creating the following trigger:

CREATE TRIGGER c_aud_trg
BEFORE INSERT OR UPDATE OR DELETE
ON ca
FOR EACH ROW
EXECUTE PROCEDURE c_aud_trg_trfunc();

It will actually get created as (using pgAdmin 1.12):
CREATE TRIGGER c_aud_trg
BEFORE INSERT OR UPDATE
ON ca
FOR EACH ROW
EXECUTE PROCEDURE c_aud_trg_func(E'\\x');

If that same trigger is dropped and re-added using what is in the database,
the following shows up:
CREATE TRIGGER c_aud_trg
BEFORE INSERT OR UPDATE
ON ca
FOR EACH ROW
EXECUTE PROCEDURE c_aud_trg_func(E'\\x5c7800');

The trigger fired normally but what is that junk argument?