language: ruby
script: bundle exec appraisal rake
rvm:
  - 2.2.10
  - 2.3.8
  - 2.4.5
  - 2.5.3
  - 2.6.1
  - jruby-9.2.5.0
before_install:
  - gem update --system
  - gem uninstall bundler --all --ignore-dependencies --executables
  - gem install bundler --version "~> 1.17"
before_script:
  - bundle exec appraisal install
env:
  - DATABASE=postgres
  - DATABASE=mysql
  - DATABASE=sqlite

language: ruby
dist: xenial
script: bundle exec appraisal rake
rvm:
  - 2.2.10
  - 2.3.8
  - 2.4.5
  - 2.5.3
  - 2.6.1
  - jruby-9.2.5.0
before_install:
  - gem install bundler --version 1.17.3
install:
  - bundle _1.17.3_ install --jobs=3 --retry=3
before_script:
  - bundle exec appraisal install
env:
  - DATABASE=postgres
  - DATABASE=mysql
  - DATABASE=sqlite
services:
- mysql
- postgresql

Use specific bundler version for install step.
Use specific bundler version for install step.

And updating to xenial for the latest Travis CI build environment.
