ASCII-8BIT vs UTF-8 failure using Sequel 3.40.0

repro.rb

#!/usr/bin/env ruby
# coding: utf-8
require "logger"
require "sequel"
require "sequel/extensions/pg_array"
require "json"

logger = Logger.new(STDERR)
logger.level = Logger::DEBUG

DB = Sequel.connect("postgres://localhost/repro", :encoding => "utf-8", :logger => logger)
DB.extend Sequel::Postgres::PGArray::DatabaseMethods

data = DB[<<-EOSQL].all
  SELECT array_agg(keyword) FROM show_market_keywords
EOSQL

puts data.to_json

repro.sql

--
-- PostgreSQL database dump
--

SET statement_timeout = 0;
SET client_encoding = 'UTF8';
SET standard_conforming_strings = on;
SET check_function_bodies = false;
SET client_min_messages = warning;

--
-- Name: show_market_keywords; Type: TABLE; Schema: public; Owner: francois; Tablespace: 
--

CREATE TABLE show_market_keywords (
    keyword text NOT NULL,
);

COPY show_market_keywords (keyword) FROM stdin;
gérantes d'estrade
\.