convert2rhel fails when "subscription-manager-initial-setup-addon" is installed

Issue

convert2rhel fails to download the subscription-manager-initial-setup-addon package and then refuses to continue. The said package is not available anymore in the CentOS repository:

Upon continuing, we will uninstall the following subscription-manager/katello-ca-consumer packages:

Package                                                        Vendor/Packager  Repository
-------                                                        ---------------  ----------
subscription-manager-initial-setup-addon-1.25.17-1.el8.x86_64  CentOS           @AppStream
 :
 :
No package subscription-manager-initial-setup-addon available.
Exiting due to strict setting.
Error: No package subscription-manager-initial-setup-addon available.
 :
 :
CRITICAL - Couldn't download the subscription-manager-initial-setup-addon package. This means we will not be able to do a complete rollback and may put the system in a broken state.
Check to make sure that the CentOS Linux repositories are enabled and the package is updated to its latest version.
If you would rather ignore this check set the environment variable 'CONVERT2RHEL_UNSUPPORTED_INCOMPLETE_ROLLBACK'.
Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/convert2rhel/main.py", line 102, in main
    pre_ponr_conversion()
  File "/usr/lib/python3.6/site-packages/convert2rhel/main.py", line 193, in pre_ponr_conversion
    subscription.replace_subscription_manager()
  File "/usr/lib/python3.6/site-packages/convert2rhel/subscription.py", line 203, in replace_subscription_manager
    remove_original_subscription_manager()
  File "/usr/lib/python3.6/site-packages/convert2rhel/subscription.py", line 222, in remove_original_subscription_manager
    utils.remove_pkgs(submgr_pkg_names, critical=False)
  File "/usr/lib/python3.6/site-packages/convert2rhel/utils.py", line 369, in remove_pkgs
    changed_pkgs_control.backup_and_track_removed_pkg(nvra)
  File "/usr/lib/python3.6/site-packages/convert2rhel/utils.py", line 316, in backup_and_track_removed_pkg
    restorable_pkg.backup()
  File "/usr/lib/python3.6/site-packages/convert2rhel/utils.py", line 581, in backup
    self.path = download_pkg(self.name, dest=BACKUP_DIR, set_releasever=False)
  File "/usr/lib/python3.6/site-packages/convert2rhel/utils.py", line 483, in download_pkg
    " 'CONVERT2RHEL_UNSUPPORTED_INCOMPLETE_ROLLBACK'." % (pkg, system_info.name)
  File "/usr/lib/python3.6/site-packages/convert2rhel/logger.py", line 146, in _critical
    sys.exit(msg)
SystemExit: Couldn't download the subscription-manager-initial-setup-addon package. This means we will not be able to do a complete rollback and may put the system in a broken state.
Check to make sure that the CentOS Linux repositories are enabled and the package is updated to its latest version.
If you would rather ignore this check set the environment variable 'CONVERT2RHEL_UNSUPPORTED_INCOMPLETE_ROLLBACK'.

WARNING - Abnormal exit! Performing rollback ...