Why does leapp upgrade fail with error "Command ['chroot', '/var/lib/leapp/el8userspace', '/bin/bash', '-c', 'su - -c update-ca-trust'] failed with exit code 1" ?

Issue

• On RHEL7, leapp preupgrade command fails with the following error, as reported in /var/log/leapp/leapp-report.txt

  Risk Factor: high (error)
  Title: Actor target_userspace_creator unexpectedly terminated with exit code: 1
  Summary: Traceback (most recent call last):
    File "/usr/lib/python2.7/site-packages/leapp/repository/actor_definition.py", line 74, in _do_run
      actor_instance.run(*args, **kwargs)
    File "/usr/lib/python2.7/site-packages/leapp/actors/__init__.py", line 289, in run
      self.process(*args)
    File "/usr/share/leapp-repository/repositories/system_upgrade/common/actors/targetuserspacecreator/actor.py", line 58, in process
      userspacegen.perform()
    File "/usr/lib/python2.7/site-packages/leapp/utils/deprecation.py", line 42, in process_wrapper
      return target_item(*args, **kwargs)
    File "/usr/share/leapp-repository/repositories/system_upgrade/common/actors/targetuserspacecreator/libraries/userspacegen.py", line 1268, in perform
      _create_target_userspace(context, indata, indata.packages, indata.files, target_repoids)
    File "/usr/share/leapp-repository/repositories/system_upgrade/common/actors/targetuserspacecreator/libraries/userspacegen.py", line 1117, in _create_target_userspace
      _prep_repository_access(context, target_path)
    File "/usr/share/leapp-repository/repositories/system_upgrade/common/actors/targetuserspacecreator/libraries/userspacegen.py", line 629, in _prep_repository_access
      run(["chroot", target_userspace, "/bin/bash", "-c", "su - -c update-ca-trust"])
    File "/usr/lib/python2.7/site-packages/leapp/libraries/stdlib/__init__.py", line 192, in run
      result=result
  CalledProcessError: Command ['chroot', '/var/lib/leapp/el8userspace', '/bin/bash', '-c', 'su - -c update-ca-trust'] failed with exit code 1.
  

• On RHEL8, leapp preupgrade command fails with the following error, as reported in /var/log/leapp/leapp-report.txt

  Risk Factor: high (error)
  Title: Cannot set the container mode for the subscription-manager.
  Summary:
  Key: 06583cd4c6f9e1629a9c1937643c3897618f33ef