Leapp preupgrade check fails with "Failed to call `grubby` to list available boot entries" error when remotely executed from Red Hat Satellite 6.

Issue

• leapp preupgrade job fails with the below error when executed from Red Hat Satellite WebUI.

  Title: Failed to call `grubby` to list available boot entries.
  Summary: {"details": "Command ['grubby', '--info', 'ALL'] failed with exit code 1.", "stderr": "Process Process-196:\nTraceback (most recent call last):\n  File \"/usr/lib64/python2.7/multiprocessing/process.py\", line 258, in _bootstrap\n    self.run()\n  File \"/usr/lib64/python2.7/multiprocessing/process.py\", line 114, in run\n    self._target(*self._args, **self._kwargs)\n  File \"/usr/lib/python2.7/site-packages/leapp/repository/actor_definition.py\", line 72, in _do_run\n    actor_instance.run(*args, **kwargs)\n  File \"/usr/lib/python2.7/site-packages/leapp/actors/__init__.py\", line 290, in run\n    self.process(*args)\n  File \"/usr/share/leapp-repository/repositories/system_upgrade/el7toel8/actors/sourcebootloaderscanner/actor.py\", line 18, in process\n    scan_source_boot_loader_configuration()\n  File \"/usr/share/leapp-repository/repositories/system_upgrade/el7toel8/actors/sourcebootloaderscanner/libraries/sourcebootloaderscanner.py\", line 87, in scan_source_boot_loader_configuration\n    entries=scan_boot_entries()\n  File \"/usr/share/leapp-repository/repositories/system_upgrade/el7toel8/actors/sourcebootloaderscanner/libraries/sourcebootloaderscanner.py\", line 41, in scan_boot_entries\n    grubby_output = run(CMD_GRUBBY_INFO_ALL, split=True)\n  File \"/usr/lib/python2.7/site-packages/leapp/libraries/stdlib/__init__.py\", line 181, in run\n    stdin=stdin, env=env, encoding=encoding)\n  File \"/usr/lib/python2.7/site-packages/leapp/libraries/stdlib/call.py\", line 217, in _call\n    os.execvpe(command[0], command, env=environ)\n  File \"/usr/lib64/python2.7/os.py\", line 353, in execvpe\n    _execvpe(file, args, env)\n  File \"/usr/lib64/python2.7/os.py\", line 380, in _execvpe\n    func(fullname, *argrest)\nOSError: [Errno 2] No such file or directory