language: ruby
rvm:
  - 2.1.10
  - 2.4.0
gemfile:
  - gemfiles/0.24.gemfile
  - gemfiles/0.25.gemfile
  - gemfiles/0.26.gemfile
  - gemfiles/0.27.gemfile
  - gemfiles/0.28.gemfile
  - gemfiles/0.29.gemfile
  - gemfiles/0.30.gemfile
  - gemfiles/0.31.gemfile
  - gemfiles/0.32.gemfile
  - gemfiles/0.33.gemfile
  - gemfiles/0.34.gemfile
  - gemfiles/0.35.gemfile
  - gemfiles/0.36.gemfile
  - gemfiles/0.37.gemfile
  - gemfiles/0.38.gemfile
  - gemfiles/0.39.gemfile
  - gemfiles/0.40.gemfile
  - gemfiles/0.41.gemfile
  - gemfiles/0.42.gemfile
  - gemfiles/0.43.gemfile
  - gemfiles/0.44.gemfile
  - gemfiles/0.45.gemfile
  - gemfiles/0.46.gemfile
  - gemfiles/0.47.gemfile

language: ruby
rvm:
  - 2.1.10
  - 2.4.0
gemfile:
  - gemfiles/0.24.gemfile
  - gemfiles/0.25.gemfile
  - gemfiles/0.26.gemfile
  - gemfiles/0.27.gemfile
  - gemfiles/0.28.gemfile
  - gemfiles/0.29.gemfile
  - gemfiles/0.30.gemfile
  - gemfiles/0.31.gemfile
  - gemfiles/0.32.gemfile
  - gemfiles/0.33.gemfile
  - gemfiles/0.34.gemfile
  - gemfiles/0.35.gemfile
  - gemfiles/0.36.gemfile
  - gemfiles/0.37.gemfile
  - gemfiles/0.38.gemfile
  - gemfiles/0.39.gemfile
  - gemfiles/0.40.gemfile
  - gemfiles/0.41.gemfile
  - gemfiles/0.42.gemfile
  - gemfiles/0.43.gemfile
  - gemfiles/0.44.gemfile
  - gemfiles/0.45.gemfile
  - gemfiles/0.46.gemfile
  - gemfiles/0.47.gemfile
before_install:
  - gem update --system

Resolve the following error in CI
Resolve the following error in CI

```
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
    can't modify frozen String
Gem files will remain installed in
/home/travis/.rvm/gems/ruby-2.4.0/gems/rainbow-2.2.1 for inspection.
Results logged to
/home/travis/.rvm/gems/ruby-2.4.0/extensions/x86_64-linux/2.4.0/rainbow-2.2.1/gem_make.out
An error occurred while installing rainbow (2.2.1), and Bundler cannot
continue.
Make sure that `gem install rainbow -v '2.2.1'` succeeds before bundling.
```

https://travis-ci.org/m4i/rubocop-git/jobs/199128529
