Unable to create a MetaPackage

I used the external_packages and external_recipes configuration items to point to a set of packages and recipes for our organization's GStreamer assets. The main Package points to the recipes, and a MetaPackage is defined like this:

# ourassets-installer.package
# vi:si:et:sw=4:sts=4:ts=4:syntax=python:ft=python
# -*- Mode: Python -*-

from cerbero.packages import package

class MetaPackage(package.MetaPackage):
    name = 'ourassets'
    shortdesc = 'Our Assets Installer'
    longdesc = shortdesc
    uuid = '7fe62402-c5a7-4b99-b73e-e4ef5c03e008'
    packages = [
        # (name, required, selected)
        ('our-plugins', True, True),
    ]

When I try to run cerbero-uninstalled ... list-packages, it dumps an error:

WARNING: Error loading package from file c:/Projects/ourassets-cerbero/packages/ourassets-installer.package
Traceback (most recent call last):
  File "C:\cerbero\packages\packagesstore.py", line 198, in _load_packages_from_file
    pkg = self._load_package_from_file(package_cls, filepath, custom)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\cerbero\packages\packagesstore.py", line 216, in _load_package_from_file
    raise Exception('Uknown package type %s' % package_cls)
Exception: Uknown package type <class 'MetaPackage'>

The error is exact; that function doesn't handle the MetaPackage class. The fix is:

     def _load_package_from_file(self, package_cls, filepath, custom=None):
         if issubclass(package_cls, package.App):
             p = package_cls(self._config, self, self.cookbook)
         elif issubclass(package_cls, package.SDKPackage):
             p = package_cls(self._config, self)
+        elif issubclass(package_cls, package.MetaPackage):
+            p = package_cls(self._config, self)
         elif issubclass(package_cls, package.InstallerPackage):
             p = package_cls(self._config, self)
         elif issubclass(package_cls, package.Package):
             p = package_cls(self._config, self, self.cookbook)
         else:
             raise Exception('Uknown package type %s' % package_cls)