RHEL7: "leapp upgrade" fails in reboot phase with message "OSError: [Errno 17] File exists: '/root/tmp_leapp_py3'" then enters emergency

Issue

• After rebooting once leapp upgrade executed successfully, the boot falls into emergency and shows the following messages on the console:

  upgrade[XXX]: Traceback (most recent call last):
  upgrade[XXX]:   File "/usr/lib64/python2.7/multiprocessing/process.py", line 258, in _bootstrap
  upgrade[XXX]:     self.run()
  upgrade[XXX]:   File "/usr/lib64/python2.7/multiprocessing/process.py", line 114, in run
  upgrade[XXX]:     self._target(*self._args, **self._kwargs)
  upgrade[XXX]:   File "/usr/lib/python2.7/site-packages/leapp/repository/actor_definition.py", line 65, in _do_run
  upgrade[XXX]:     skip_dialogs=skip_dialogs).run(*args, **kwargs)
  upgrade[XXX]:   File "/usr/lib/python2.7/site-packages/leapp/actors/__init__.py", line 335, in run
  upgrade[XXX]:     self.process(*args)
  upgrade[XXX]:   File "/usr/share/leapp-repository/repositories/system_upgrade/el7toel8/actors/preparepythonworkround/actor.py", line 25, in process
  upgrade[XXX]:     os.mkdir(leapp_home)
  upgrade[XXX]: OSError: [Errno 17] File exists: '/root/tmp_leapp_py3'
  

• The issue happens when attempting a new upgrade after the first upgrade failed without re-running leapp upgrade