rvm:
  - 2.2.9
  - 2.3.8
  - 2.4.5
  - 2.5.3
  - ruby-head

addons:
  firefox: latest

# whitelist
branches:
  only:
    - master

gemfile:
  - gemfiles/rails_5_2.gemfile
  - gemfiles/rails_5_1.gemfile
  - gemfiles/rails_5_0.gemfile
  - gemfiles/rails_4_2.gemfile

matrix:
  fast_finish: true
  allow_failures:
    - rvm: ruby-head
  exclude:
    - rvm: ruby-head
      gemfile: gemfiles/rails_4_2.gemfile

before_install:
  - gem update --remote bundler
  - bin/install_geckodriver.sh

before_script: geckodriver -V

rvm:
  - 2.2.9
  - 2.3.8
  - 2.4.5
  - 2.5.3
  - ruby-head

addons:
  firefox: latest

# whitelist
branches:
  only:
    - master

gemfile:
  - gemfiles/rails_5_2.gemfile
  - gemfiles/rails_5_1.gemfile
  - gemfiles/rails_5_0.gemfile
  - gemfiles/rails_4_2.gemfile

matrix:
  fast_finish: true
  allow_failures:
    - rvm: ruby-head

before_install:
  - gem update --remote bundler
  - bin/install_geckodriver.sh

before_script: geckodriver -V

Revert "Exclude Rails 4.2 + ruby-head (2.6) build"
Revert "Exclude Rails 4.2 + ruby-head (2.6) build"

## Summary

This reverts commit e4b7e5fd11f042c5fc532b9798a0ae5faf130e61.

## Details

This PR restores Rails 4.2 + ruby-head (2.6) build.

`BigDecimal.new` has been replaced with deprecation rather than deletion.

```console
% ruby -rbigdecimal -ve 'BigDecimal.new(42)'
ruby 2.6.0dev (2018-12-24 trunk 66524) [x86_64-darwin17]
-e:1: warning: BigDecimal.new is deprecated; use BigDecimal() method instead.
```

## Motivation and Context

Follow up of https://github.com/cucumber/cucumber-rails/pull/400#issuecomment-447177153.
