Merge pull request #147 from da-ar/bundler_travis_fix

(maint) Bundler 2.0 dropped support for Ruby versions < 2.2

Author: da-ar

.travis.yml

@@ -45,13 +45,21 @@ matrix:
     - rvm: 2.4.1
       env: PUPPET_GEM_VERSION='~> 5.0.0'
     - rvm: 2.1.9
-      env: PUPPET_GEM_VERSION='~> 4' COVERAGE=yes # 4.10
+      env: PUPPET_GEM_VERSION='~> 4'  COVERAGE=yes # 4.10
+      before_install:
+        - gem install bundler -v '< 2'
     - rvm: 2.1.9
       env: PUPPET_GEM_VERSION='~> 4.9.0'
+      before_install:
+        - gem install bundler -v '< 2'
     - rvm: 2.1.9
       env: PUPPET_GEM_VERSION='~> 4.8.0'
+      before_install:
+        - gem install bundler -v '< 2'
     - rvm: 2.1.9
       env: PUPPET_GEM_VERSION='~> 4.7.0'
+      before_install:
+        - gem install bundler -v '< 2'
     - rvm: 2.5.1
       env: PUPPET_GEM_VERSION='https://github.com/puppetlabs/puppet.git#master'
     - rvm: 2.5.1