Do not redirect Travis output to /dev/null

.travis.yml

@@ -11,5 +11,5 @@ services:
   - docker
 before_script:
   - sudo sysctl -w vm.max_map_count=262144
-  - docker run --rm --privileged=true -p 9200:9200 -p 9300:9300 -e "bootstrap.memory_lock=true" -e "ES_JAVA_OPTS=-Xms1g -Xmx1g" docker.elastic.co/elasticsearch/elasticsearch:5.4.1 elasticsearch -Expack.security.enabled=false -Escript.inline=true -Escript.stored=true -Escript.file=true -Enetwork.host=_local_,_site_ -Enetwork.publish_host=_local_ >& /dev/null &
+  - docker run --rm --privileged=true -p 9200:9200 -p 9300:9300 -e "bootstrap.memory_lock=true" -e "ES_JAVA_OPTS=-Xms1g -Xmx1g" docker.elastic.co/elasticsearch/elasticsearch:5.4.1 elasticsearch -Expack.security.enabled=false -Escript.inline=true -Escript.stored=true -Escript.file=true -Enetwork.host=_local_,_site_ -Enetwork.publish_host=_local_ &
   - sleep 15