Unable to import custom python modules when using the slack backend.

Describe the bug Errbot running on python 3.11 in docker, using the slackv3 backend is unable to load a python library into a plugin

To Reproduce plugin code:

from lib.chatutils import ChatUtils
from errbot import BotPlugin, botcmd

chatutils = ChatUtils()

class MyTest(BotPlugin):
    """Perform system level commands"""

    @botcmd()
    def am_i_admin(self, msg, _):
        admin = chatutils.is_admin(msg)
        return f"{chatutils.handle(msg)} {admin}"

python library (in plugins/lib/chatutils.py)

import os
import re

class ChatUtils:
    """
    A collection of common utilities used throughout the repo
    """
    def is_admin(self, msg, admins):
        if self.handle(msg) in admins:
            return True
        return False

    def handle(self, msg):
        try:
            return str(msg.frm).split("/")[1]
        except:
            return msg.frm

Expected behavior Errbot should load the plugin.

Actual behavior

2024-04-22 19:54:18,251 INFO     errbot.core               Some plugins failed to start during bot startup:

Traceback (most recent call last):
  File "/errbot-data/lib/python3.11/site-packages/errbot/plugin_manager.py", line 289, in _load_plugins_generic
    plugin_classes = plugin_info.load_plugin_classes(
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/errbot-data/lib/python3.11/site-packages/errbot/plugin_info.py", line 100, in load_plugin_classes
    spec.loader.exec_module(modu1e)
  File "<frozen importlib._bootstrap_external>", line 940, in exec_module
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "/errbot-data/eks-ops/errbot/plugins/mytest/mytest.py", line 5, in <module>
    import lib.chatutils
ModuleNotFoundError: No module named 'lib.chatutils'; 'lib' is not a package
Error: MyTest failed to activate: 'NoneType' object has no attribute 'is_activated'.

Environment (please complete the following information):

Errbot version: 6.2.0
OS version: Debian 12
Python version: Python 3.11.2
Using a virtual environment: yes
Using Docker: yes

Additional context

Config.py includes a reference to plugins, and sys.path via errbot returns:

Path: ['/errbot-data/code', '/errbot-data/code', '/errbot-data/bin', '/usr/lib/python311.zip', '/usr/lib/python3.11', '/usr/lib/python3.11/lib-dynload', '/errbot-data/lib/python3.11/site-packages', '/errbot-data/lib/python3.11/site-packages/errbot/storage', '/errbot-data/eks-ops/errbot/backends/err-backend-slackv3/src/slackv3', '/errbot-data/lib/python3.11/site-packages/errbot/core_plugins', '/errbot-data/eks-ops/errbot/plugins/mytest', '/errbot-data/eks-ops/errbot/plugins/ops', '/errbot-data/eks-ops/errbot/plugins/Git', '/errbot-data/eks-ops/errbot/plugins']

This includes (last entry) the plugins/ dir in the search path.

When using backend Text (or Discord) this error does not occur.

errbotio / err-backend-slackv3

Unable to import custom python modules when using the slack backend. #105