allow php7.1 to fail

.travis.yml

@@ -44,6 +44,7 @@ matrix:
 
   allow_failures:
     - php: hhvm
+    - php: 7.1
 
 before_install:
   - if [ $HHVM != 1 && $TRAVIS_PHP_VERSION != 7.* ]; then phpenv config-rm xdebug.ini; fi