title: Rubocop doesn't see Gemfile
body: <p>I have configured <a href="https://github.com/bbatsov/rubocop" rel="nofollow noreferrer">rubocop</a> gem into my project with git commit hook using <a href="https://github.com/observing/pre-commit" rel="nofollow noreferrer">pre-commit</a> and I have faced the problem: rubocop evaluating on commit hook checks Gemfile but when I manually run <code>rubocop</code> in project's directory it isn't check it. Actually when I run <code>rubocop Gemfile</code> it works but it's so inconvenient for me... Maybe someone has already solved this problem?</p>