.travis.yml in public_suffix-3.1.0 vs .travis.yml in public_suffix-3.1.1

@@ -13,9 +13,16 @@
 
 cache:
   - bundler
 
 matrix:
+  include:
+    - rvm: 2.1
+      before_install:
+        - gem install bundler -v '< 2.0'
+    - rvm: 2.2
+      before_install:
+        - gem install bundler -v '< 2.0'
   allow_failures:
     - rvm: ruby-head
     - rvm: jruby-9.1.5.0
 
 before_install: