idle_start never returns if the server closes the connection

[bipface]

When calling idle_start(), if the server closes the connection instead of responding with + idling, the function will hang indefinitely (regardless of the timeout arg).
Tested using aioimaplib v1.1.0, python v3.11.2.

I experienced this issue when connected to imap.gmx.com, however the following code demonstrates the bug in isolation.

Log when the server responds normally (no issue):

[root:DEBUG] idle_start()
[aioimaplib.aioimaplib:DEBUG] Sending : b'EMNN3 IDLE\r\n'
[aioimaplib.aioimaplib:DEBUG] Received : b'+ idling\r\n'
[aioimaplib.aioimaplib:DEBUG] continuation line -- assuming IDLE is active : b'+ idling'
[root:DEBUG] wait_server_push()
[root:DEBUG] Timeout - wait_server_push
[aioimaplib.aioimaplib:DEBUG] connection lost: None
[root:DEBUG] onConnLost()
<process exits here>

Log when the connection is closed:

[root:DEBUG] idle_start()
[aioimaplib.aioimaplib:DEBUG] Sending : b'GGPL3 IDLE\r\n'
[aioimaplib.aioimaplib:DEBUG] Received : b'* BYE timeout\r\n'
[aioimaplib.aioimaplib:DEBUG] connection lost: None
[root:DEBUG] onConnLost()
<process is still running and never exits>

Code:

import asyncio
import logging
import logging.config
import socket
import aioimaplib
import threading
import re

async def testIdle() -> None:
	configureLogging()

	evt = threading.Event()
	svrThread = threading.Thread(target=imapServer, args=(evt,))
	svrThread.start()
	
	imap = aioimaplib.IMAP4(
		host='127.0.0.1',
		port=8000,
		conn_lost_cb=onConnLost,
	)
	
	await imap.wait_hello_from_server()
	await imap.login('foo', 'bar')
	await imap.select('INBOX')
	
	logging.debug('idle_start()')
	idleTask = await imap.idle_start()

	logging.debug('wait_server_push()')
	try:
		data = await imap.wait_server_push(timeout=3)
		logging.debug('wait_server_push result: %s', repr(data))
	except TimeoutError:
		logging.debug('Timeout - wait_server_push')
	
	evt.set()
	svrThread.join()
	
def onConnLost(*args) -> None:
	logging.debug('onConnLost()')

def imapServer(evt) -> None:
	svr = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
	svr.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
	svr.bind(('127.0.0.1', 8000))
	svr.listen(1)

	svr.settimeout(1)

	logging.debug('svr.accept()')
	client = svr.accept()[0]
	svr.close()

	client.send(b'* OK\r\n')

	data = client.recv(1024)
	m = re.fullmatch(b'^(\w+) CAPABILITY\r\n$', data)
	client.send(b'* CAPABILITY IMAP4rev1 IDLE\r\n')
	client.send(m[1] + b' OK CAPABILITY completed\r\n')

	data = client.recv(1024)
	m = re.fullmatch(b'^(\w+) LOGIN [^\r]+\r\n$', data)
	client.send(m[1] + b' OK LOGIN completed\r\n')

	data = client.recv(1024)
	m = re.fullmatch(b'^(\w+) SELECT INBOX\r\n$', data)
	client.send(m[1] + b' OK SELECT completed\r\n')

	data = client.recv(1024)
	m = re.fullmatch(b'^(\w+) IDLE\r\n$', data)
	if not m:
		raise Exception
		
	if False:
		# Normal response:
		client.send(b'+ idling\r\n')
		evt.wait()
		client.close()
	else:
		# Pathological response:
		client.send(b'* BYE timeout\r\n')
		client.close()
		evt.wait()

def configureLogging() -> None:
	logging.config.dictConfig({
		'version': 1,
		'disable_existing_loggers': False,
		'formatters': {
			'default': {
				'format': '[%(name)s:%(levelname)s] %(message)s',
			},
		},
		'handlers': {
			'stderr': {
				'class': 'logging.StreamHandler',
				'formatter': 'default',
				'stream': 'ext://sys.stderr',
			},
		},
		'root': {
			'level': 'DEBUG',
			'handlers': ['stderr'],
		},
	})

if __name__ == '__main__':
	asyncio.run(testIdle())