Node-Postgres client.end + pool.end hanging

index.js

const pg = require('pg');

async function f (callback) {
  const pool = new pg.Pool;
  const connection = await pool.connect();
  await callback(connection);
  await connection.end();
  await pool.end(); // Commenting this line will prevent the hang.
}

(async () => {
  await f(async connection => {
    console.log('X');
  });
  console.log('Y'); // Never runs unless line 8 is commented.
})();