Tee and StdOut modes seem to have no effect

[ferm10n]

When running with Deno 1.3.0, the Tee and StdOut modes seem to have no effect.

import { exec, OutputMode } from "https://deno.land/x/[email protected]/mod.ts";

const p1 = await exec('bash -c echo one && sleep 1 && echo two', { output: OutputMode.Tee }); // displays nothing
console.log(await p1.output); // displays nothing
const p2 = await exec('bash -c echo one && sleep 1 && echo two', { output: OutputMode.StdOut }); // displays nothing
console.log(await p2.output); // displays nothing

Commands starting with bash -c ... seem to have an impact. Running something simple, like exec('echo hello', { output: OutputMode.StdOut }); works as expected. So does this command bash --help, so it's probably not related to calling bash itself