.travis.yml in sig-1.0.0 vs .travis.yml in sig-1.0.1

@@ -5,13 +5,15 @@
 
 rvm:
 - 2.2
 - 2.1
 - rbx-2
+- ruby-head
 - jruby-9000
 
 cache:
 - bundler
 
 matrix:
   allow_failures:
+    - rvm: ruby-head
     - rvm: jruby-9000