Another try at getting Travis happy.

.travis.yml

@@ -22,10 +22,6 @@ env:
 matrix:
   allow_failures:
     - env:
-      - distribution: centos
-        version: 6
-        init: /sbin/init
-        run_opts: ""
       - distribution: centos
         version: 7
         init: /usr/lib/systemd/systemd