Why does the leapp preupgrade fails with "FileNotFoundError: [Errno 2] No such file or directory: 'systemd-nspawn'"?

Issue

• leapp preupgrade fails with the below error:

  Risk Factor: high (error)
  Title: Actor target_userspace_creator unexpectedly terminated with exit code: 1
  Summary: Traceback (most recent call last):
   File "/usr/lib/python3.6/site-packages/leapp/repository/actor_definition.py", line 74, in _do_run
  actor_instance.run(*args, **kwargs)
   File "/usr/lib/python3.6/site-packages/leapp/actors/__init__.py", line 289, in run
  self.process(*args)
   File "/etc/leapp/repos.d/system_upgrade/common/actors/targetuserspacecreator/actor.py", line 58, in process
  userspacegen.perform()
   File "/usr/lib/python3.6/site-packages/leapp/utils/deprecation.py", line 42, in process_wrapper
  return target_item(*args, **kwargs)
   File "/etc/leapp/repos.d/system_upgrade/common/actors/targetuserspacecreator/libraries/userspacegen.py", line 856, in perform
  target_repoids = _gather_target_repositories(context, indata, prod_cert_path)
   File "/etc/leapp/repos.d/system_upgrade/common/actors/targetuserspacecreator/libraries/userspacegen.py", line 791, in _gather_target_repositories
  rhsm.set_container_mode(context)
   File "/etc/leapp/repos.d/system_upgrade/common/libraries/rhsm.py", line 352, in set_container_mode
  context.call(['ln', '-s', '/etc/rhsm', '/etc/rhsm-host'])
   File "/etc/leapp/repos.d/system_upgrade/common/libraries/mounting.py", line 168, in call
  return run(self.type.make_command(cmd), *args, **kwargs)
   File "/usr/lib/python3.6/site-packages/leapp/libraries/stdlib/__init__.py", line 185, in run
  stdin=stdin, env=env, encoding=encoding)
   File "/usr/lib/python3.6/site-packages/leapp/libraries/stdlib/call.py", line 145, in _call
  raise OSError(errno.ENOENT, os.strerror(errno.ENOENT), command[0])
  FileNotFoundError: [Errno 2] No such file or directory: 'systemd-nspawn'