leapp preupgrade fails with error in _get_sysctls ValueError: too many values to unpack

Issue

• When trying to upgrade RHEL 7 to RHEL 8, a python traceback is written:

  $ leapp preupgrade  
  ...
  ====> * system_facts
          Provides data about many facts from system.
  Process Process-219:
  Traceback (most recent call last):
    File "/usr/lib64/python2.7/multiprocessing/process.py", line 258, in _bootstrap
      self.run()
    File "/usr/lib64/python2.7/multiprocessing/process.py", line 114, in run
      self._target(*self._args, **self._kwargs)
    File "/usr/lib/python2.7/site-packages/leapp/repository/actor_definition.py", line 72, in _do_run
      actor_instance.run(*args, **kwargs)
    File "/usr/lib/python2.7/site-packages/leapp/actors/__init__.py", line 335, in run
      self.process(*args)
    File "/usr/share/leapp-repository/repositories/system_upgrade/common/actors/systemfacts/actor.py", line 36, in process
      self.produce(systemfacts.get_sysctls_status())
    File "/usr/share/leapp-repository/repositories/system_upgrade/common/actors/systemfacts/libraries/systemfacts.py", line 170, in get_sysctls_status
      return SysctlVariablesFacts(sysctl_variables=_get_sysctls())
    File "/usr/share/leapp-repository/repositories/system_upgrade/common/actors/systemfacts/libraries/systemfacts.py", line 22, in inner
      return list(f(*args, **kwargs))
    File "/usr/share/leapp-repository/repositories/system_upgrade/common/actors/systemfacts/libraries/systemfacts.py", line 152, in _get_sysctls
      name, value = tuple(map(type(var).strip, var.split('=')))
  ValueError: too many values to unpack