use nightly tag to pull openwhisk core images (#450)
diff --git a/tools/travis/test_openwhisk.sh b/tools/travis/test_openwhisk.sh
index 698fdd2..a6840a7 100755
--- a/tools/travis/test_openwhisk.sh
+++ b/tools/travis/test_openwhisk.sh
@@ -85,7 +85,7 @@
# Fire up the cluster
cd $OPENWHISK_HOME/ansible
-ANSIBLE_CMD="ansible-playbook -i environments/local -e docker_image_prefix=openwhisk"
+ANSIBLE_CMD="ansible-playbook -i environments/local -e docker_image_prefix=openwhisk -e docker_image_tag=nightly"
$ANSIBLE_CMD setup.yml
$ANSIBLE_CMD prereq.yml
$ANSIBLE_CMD couchdb.yml