Traceback (most recent call last):
  File "/usr/lib/update-notifier/list-oem-metapackages", line 54, in <module>
    if any_oem_metapackages_installed(cache):
  File "/usr/lib/update-notifier/list-oem-metapackages", line 19, in any_oem_metapackages_installed
    installed_oem_packages = (
TypeError: 'apt_pkg.Cache' object is not iterable