"LookupError: No installed app with label" during "final" container startup with plugin(s) installed

[glennmatthews]

Environment

• Python version: 3.7
• Nautobot version: 1.1.1

Steps to Reproduce

1. Build non-dev image (i.e. build target final).
2. Add at least one plugin to the image and enable it in PLUGINS in the nautobot_config.py
3. Start the container
4. Run nautobot-server with any subcommand (even nautobot-server help)

Expected Behavior

nautobot-server commands should work

Observed Behavior

root@aeba69afb96f:/opt/nautobot# nautobot-server help
2021-08-05 19:03:33,819 DEBUG Popen(['git', 'version'], cwd=/opt/nautobot, universal_newlines=False, shell=None, istream=None) - git.cmd - cmd - /usr/local/lib/python3.7/site-packages/git/cmd.py:811
2021-08-05 19:03:33,825 DEBUG Popen(['git', 'version'], cwd=/opt/nautobot, universal_newlines=False, shell=None, istream=None) - git.cmd - cmd - /usr/local/lib/python3.7/site-packages/git/cmd.py:811
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/django/apps/registry.py", line 156, in get_app_config
    return self.app_configs[app_label]
KeyError: 'my_plugin_name'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/bin/nautobot-server", line 8, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.7/site-packages/nautobot/core/cli.py", line 62, in main
    initializer=_configure_settings,  # Called after defaults
  File "/usr/local/lib/python3.7/site-packages/nautobot/core/runner/runner.py", line 266, in run_app
    management.execute_from_command_line([runner_name, command] + command_args)
  File "/usr/local/lib/python3.7/site-packages/django/core/management/__init__.py", line 401, in execute_from_command_line
    utility.execute()
  File "/usr/local/lib/python3.7/site-packages/django/core/management/__init__.py", line 377, in execute
    django.setup()
  File "/usr/local/lib/python3.7/site-packages/django/__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/usr/local/lib/python3.7/site-packages/django/apps/registry.py", line 122, in populate
    app_config.ready()
  File "/usr/local/lib/python3.7/site-packages/nautobot/circuits/apps.py", line 9, in ready
    super().ready()
  File "/usr/local/lib/python3.7/site-packages/nautobot/core/apps/__init__.py", line 34, in ready
    register_menu_items(menu_items)
  File "/usr/local/lib/python3.7/site-packages/nautobot/core/apps/__init__.py", line 73, in register_menu_items
    reverse(item.link)
  File "/usr/local/lib/python3.7/site-packages/django/urls/base.py", line 55, in reverse
    app_list = resolver.app_dict[ns]
  File "/usr/local/lib/python3.7/site-packages/django/urls/resolvers.py", line 522, in app_dict
    self._populate()
  File "/usr/local/lib/python3.7/site-packages/django/urls/resolvers.py", line 456, in _populate
    for url_pattern in reversed(self.url_patterns):
  File "/usr/local/lib/python3.7/site-packages/django/utils/functional.py", line 48, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/usr/local/lib/python3.7/site-packages/django/urls/resolvers.py", line 589, in url_patterns
    patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
  File "/usr/local/lib/python3.7/site-packages/django/utils/functional.py", line 48, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/usr/local/lib/python3.7/site-packages/django/urls/resolvers.py", line 582, in urlconf_module
    return import_module(self.urlconf_name)
  File "/usr/local/lib/python3.7/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
  File "<frozen importlib._bootstrap>", line 983, in _find_and_load
  File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 728, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/usr/local/lib/python3.7/site-packages/nautobot/core/urls.py", line 7, in <module>
    from nautobot.extras.plugins.urls import (
  File "/usr/local/lib/python3.7/site-packages/nautobot/extras/plugins/urls.py", line 32, in <module>
    app = apps.get_app_config(plugin_name)
  File "/usr/local/lib/python3.7/site-packages/django/apps/registry.py", line 163, in get_app_config
    raise LookupError(message)
LookupError: No installed app with label 'my_plugin_name'.