Python's modulefinder package chokes on new versions of cherrypy - AttributeError: 'NoneType' object has no attribute 'is_package'

[Melnorme1984]

I work on a system that until now has used an old version of cherrypy (v8.9.1). We use Python's modulefinder package to resolve dependencies when building our executables. Currently we're upgrading the system to Python 3.11, which we found required us to upgrade to a new version of cherrypy (due to the use of getargspec). Unfortunately it seems modulefinder doesn't play nicely with v18.8.0 and presumably other newer versions.

  File "/usr/lib/python3.11/modulefinder.py", line 160, in load_file
    self.load_module(name, fp, pathname, stuff)
  File "/usr/lib/python3.11/modulefinder.py", line 349, in load_module
    self.scan_code(co, m)
  File "/usr/lib/python3.11/modulefinder.py", line 411, in scan_code
    self._safe_import_hook(name, m, fromlist, level=0)
  File "/usr/lib/python3.11/modulefinder.py", line 367, in _safe_import_hook
    self.import_hook(name, caller, level=level)
  File "/usr/lib/python3.11/modulefinder.py", line 165, in import_hook
    q, tail = self.find_head_package(parent, name)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/modulefinder.py", line 221, in find_head_package
    q = self.import_module(head, qname, parent)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/modulefinder.py", line 315, in import_module
    m = self.load_module(fqname, fp, pathname, stuff)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/modulefinder.py", line 328, in load_module
    m = self.load_package(fqname, pathname)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/modulefinder.py", line 460, in load_package
    self.load_module(fqname, fp, buf, stuff)
  File "/usr/lib/python3.11/modulefinder.py", line 349, in load_module
    self.scan_code(co, m)
  File "/usr/lib/python3.11/modulefinder.py", line 434, in scan_code
    self._safe_import_hook(name, m, fromlist, level=level)
  File "/usr/lib/python3.11/modulefinder.py", line 367, in _safe_import_hook
    self.import_hook(name, caller, level=level)
  File "/usr/lib/python3.11/modulefinder.py", line 165, in import_hook
    q, tail = self.find_head_package(parent, name)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/modulefinder.py", line 221, in find_head_package
    q = self.import_module(head, qname, parent)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/modulefinder.py", line 315, in import_module
    m = self.load_module(fqname, fp, pathname, stuff)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/modulefinder.py", line 349, in load_module
    self.scan_code(co, m)
  File "/usr/lib/python3.11/modulefinder.py", line 411, in scan_code
    self._safe_import_hook(name, m, fromlist, level=0)
  File "/usr/lib/python3.11/modulefinder.py", line 382, in _safe_import_hook
    self.import_hook(name, caller, [sub], level=level)
  File "/usr/lib/python3.11/modulefinder.py", line 170, in import_hook
    self.ensure_fromlist(m, fromlist)
  File "/usr/lib/python3.11/modulefinder.py", line 260, in ensure_fromlist
    submod = self.import_module(sub, subname, m)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/modulefinder.py", line 315, in import_module
    m = self.load_module(fqname, fp, pathname, stuff)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/modulefinder.py", line 349, in load_module
    self.scan_code(co, m)
  File "/usr/lib/python3.11/modulefinder.py", line 411, in scan_code
    self._safe_import_hook(name, m, fromlist, level=0)
  File "/usr/lib/python3.11/modulefinder.py", line 367, in _safe_import_hook
    self.import_hook(name, caller, level=level)
  File "/usr/lib/python3.11/modulefinder.py", line 165, in import_hook
    q, tail = self.find_head_package(parent, name)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/modulefinder.py", line 221, in find_head_package
    q = self.import_module(head, qname, parent)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/modulefinder.py", line 308, in import_module
    fp, pathname, stuff = self.find_module(partname,
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/modulefinder.py", line 489, in find_module
    return _find_module(name, path)
           ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/modulefinder.py", line 69, in _find_module
    if spec.loader.is_package(name):
       ^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'is_package'

Are we doing something wrong or is this a bug? There is a known issue in Python caused by namespace packages: https://bugs.python.org/issue40350

But I'm not sure if that's relevant here.