Leapp preupgrade fails with `ImportError: cannot import name report_inhibitors` error when performing in-place upgrade of Red Hat Satellite 6.11 server

Issue

• Following the procedure outlined in Chapter 4. Upgrading Satellite or Capsule to Red Hat Enterprise Linux 8 In-Place Using Leapp to perform a leapp upgrade of Red Hat Satellite 6.11 server, the leapp preupgrade command in step (6) failed with the following backtrace:

  # leapp preupgrade
  Traceback (most recent call last):
  File "/bin/leapp", line 9, in <module>
    load_entry_point('leapp==0.16.0', 'console_scripts', 'leapp')()
  File "/usr/lib/python2.7/site-packages/leapp/cli/__init__.py", line 43, in main
    _load_commands(cli.command)
  File "/usr/lib/python2.7/site-packages/leapp/cli/__init__.py", line 27, in _load_commands
    package = pkgutil.get_loader(package_name).load_module(package_name)
  File "/usr/lib64/python2.7/pkgutil.py", line 246, in load_module
    mod = imp.load_module(fullname, self.file, self.filename, self.etc)
  File "/usr/lib/python2.7/site-packages/leapp/cli/commands/list_runs/__init__.py", line 6, in <module>
    from leapp.cli.commands.upgrade.util import fetch_all_upgrade_contexts
  File "/usr/lib/python2.7/site-packages/leapp/cli/commands/upgrade/__init__.py", line 12, in <module>
    from leapp.utils.output import beautify_actor_exception, report_errors, report_info, report_inhibitors
  ImportError: cannot import name report_inhibitors