Asyncio code finishes in Python3.8/9, but not Python 3.6.1 (reproducible example included)

Question

The code below is a reproducible example of code I need to backport to 3.6.1 (because that is what I can use on the university cluster).

This is code that runs async code in a different thread so that the REPL is not affected.

If I run it in the IPython3.8/3.9 REPLs, the coroutine finishes. If I run it in 3.6.1 it only runs until await proc.communicate().

However, if I add a asyncio.get_event_loop().run_until_complete(asyncio.gather(dummy())) the finish messages show up.

Remember that this code is meant to be used from the REPL where I want processing to be done async in another thread so my REPL is always responsive.

import asyncio
import atexit

from datetime import datetime
from threading import Thread

asyncio.get_child_watcher()
asyncio.get_event_loop()

def _start_loop(loop):
    asyncio.set_event_loop(loop)
    loop.run_forever()

background_loop = asyncio.new_event_loop()
thread = Thread(target=_start_loop, args=(background_loop,))
thread.daemon = True
thread.start()

async def dummy():
    await asyncio.sleep(0.001)

def run_background_task(coroutine, loop):
    return asyncio.run_coroutine_threadsafe(coroutine, loop)

async def test_task(whence):
    now = datetime.now()

    current_time = now.strftime("%H:%M:%S")

    print(f"started {whence} @ {current_time}")
    proc = await asyncio.subprocess.create_subprocess_shell(f"touch {whence}; echo hi; sleep 1; echo ho",
                                                           stderr=asyncio.subprocess.PIPE,
                                                           stdout=asyncio.subprocess.PIPE)
    (stdout, stderr) = await proc.communicate()
    stdout, stderr = stdout.decode(), stderr.decode()
    print(f"stdout: {stdout}")
    print(f"stderr: {stderr}")

    now = datetime.now()

    current_time = now.strftime("%H:%M:%S")

    print(f"finished {whence} @ {current_time}")

    return proc, stdout, stderr

background_task = run_background_task(
    test_task("background_task"), background_loop
)

Is there a reason why? In Python 3.6.1 it only prints the start message, none of the following ones.