pg_dump failure with 9.3 server

I have found a problem with pg_dump (9.3 and 9.4) against a specially
crafted 9.3 database.

This is not a critical bug for me.

Here is a capture from an xterm session, showing the full sequence of
commands to reproduce the problem.

marc:skit$ psql
psql (9.4.0, server 9.3.5)
Type "help" for help.

postgres=# drop database regressdb;
DROP DATABASE
postgres=# create database regressdb;
CREATE DATABASE
postgres=# \q
marc:skit$ psql -d regressdb
psql (9.4.0, server 9.3.5)
Type "help" for help.

regressdb=# create
regressdb-# function ddl_notice() returns event_trigger as
regressdb-# $$
regressdb$# begin
regressdb$# raise notice 'DDL!!!!!!';
regressdb$# end;
regressdb$# $$
regressdb-# language plpgsql;
CREATE FUNCTION
regressdb=#
regressdb=#
regressdb=# create event trigger ddl_notice on ddl_command_start
regressdb-# when tag in ('DROP FUNCTION')
regressdb-# execute procedure ddl_notice();
CREATE EVENT TRIGGER
regressdb=#
regressdb=# alter event trigger ddl_notice disable;
ALTER EVENT TRIGGER
regressdb=#
regressdb=# comment on event trigger ddl_notice is
regressdb-# 'an event trigger';
COMMENT
regressdb=# \q
marc:skit$ pg_dump regressdb >x
cannot duplicate null pointer (internal error)
marc:skit$

This is on debian 7.7 with the following packages installed:

dpkg info:
postgresql-client-9.4 9.4.0-1.pgdg70+1
postgresql-9.3 9.3.5-2.pgdg70+1

uname -a:
Linux bloodnok 3.6.3-upstream #1 SMP Tue Nov 13 16:18:51 PST 2012 x86_64 GNU/Linux

Also reproduced on my i686 laptop with pg9.3 client and server.

The problem seems to be related to the comment on the event trigger. If
I remove the comment, the failure no longer occurs.

__
Marc