When you use inherit_from with a remote config, and that config inherits itself, it's possible a overridden config warning would be triggered. However, PathUtil#smart_path does not expect a RemoteConfig, and thus was crashing.

undefined method `start_with?' for an instance of RuboCop::RemoteConfig
/src/rubocop/lib/rubocop/path_util.rb:42:in `smart_path'
/src/rubocop/lib/rubocop/config_loader_resolver.rb:178:in `duplicate_setting_warning'
/src/rubocop/lib/rubocop/config_loader_resolver.rb:174:in `warn_on_duplicate_setting'

I made two changes:

1. PathUtil#smart_path will no longer crash when given a RemoteConfig
2. The warning is no longer shown when looking at remote inheritence, because these files are not changable within the project. We already do the inverse when a local configuration is overridden remotely.

Before submitting the PR make sure the following are checked:

• The PR relates to only one subject with a clear title and description in grammatically correct, complete sentences.
• Wrote good commit messages.
• Commit message starts with [Fix #issue-number] (if the related issue exists).
• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Ran bundle exec rake default. It executes all tests and runs RuboCop on its own code.
• Added an entry (file) to the changelog folder named {change_type}_{change_description}.md if the new code introduces user-observable changes. See changelog entry format for details.