bbatsov/rubocop

### Bugs fixed

* [#1638](https://github.com/rubocop/rubocop/issues/1638): Use Parser functionality rather than regular expressions for matching comments in `FirstParameterIndentation`. ([@jonas054][])
* [#1642](https://github.com/rubocop/rubocop/issues/1642): Raise the correct exception if the configuration file is malformed. ([@bquorning][])
* [#1647](https://github.com/rubocop/rubocop/issues/1647): Skip `SpaceAroundBlockParameters` when lambda has no argument. ([@eitoball][])
* [#1649](https://github.com/rubocop/rubocop/issues/1649): Handle exception assignments in `UselessSetterCall`. ([@bbatsov][])
* [#1644](https://github.com/rubocop/rubocop/issues/1644): Don't search the entire file system when a folder is named `,`. ([@bquorning][])

[@bbatsov]: https://github.com/bbatsov
[@jonas054]: https://github.com/jonas054
[@bquorning]: https://github.com/bquorning
[@eitoball]: https://github.com/eitoball