.travis.yml in store_attribute-0.5.1 vs .travis.yml in store_attribute-0.5.2

@@ -8,7 +8,12 @@
   - createdb store_attribute_test
   - psql -U postgres -d store_attribute_test -c 'CREATE EXTENSION IF NOT EXISTS hstore;'
 
 matrix:
   include:
-    - rvm: 2.3.1
+    - rvm: 2.4.1
       gemfile: gemfiles/rails5.gemfile
+    - rvm: ruby-head
+      gemfile: gemfiles/railsmaster.gemfile
+  allow_failures:
+    - rvm: ruby-head
+      gemfile: gemfiles/railsmaster.gemfile