sudo: false
language: ruby
cache: bundler
rvm:
  - 2.1.10
  - 2.2.10
  - 2.3.7
  - 2.4.4
  - 2.5.1
  - ruby-head
before_install:
  - gem update --system
  - gem install bundler --no-document

sudo: false
language: ruby
cache: bundler
rvm:
  - 2.1.10
  - 2.2.10
  - 2.3.8
  - 2.4.5
  - 2.5.3
  - 2.6.0
  - ruby-head
before_install:
  - gem update --system || echo "Skipping rubygems upgrade"
  - gem install bundler --no-document

Fix Travis failures for old rubies; add new rubies
Fix Travis failures for old rubies; add new rubies

Ruby < 2.3 is no longer supported by rubygems, so gracefully ignore
rubygems upgrade failures for those versions. Also add latest Ruby patch
releases and Ruby 2.6.0 to the build matrix.
