use nightly tag to pull docker images for core openwhisk (#1060)
diff --git a/tools/travis/script.sh b/tools/travis/script.sh
index 43121bd..7f2e42b 100755
--- a/tools/travis/script.sh
+++ b/tools/travis/script.sh
@@ -44,7 +44,7 @@
cd $WHISKDIR
./tools/travis/setup.sh
-ANSIBLE_CMD="ansible-playbook -i ${ROOTDIR}/ansible/environments/local -e docker_image_prefix=openwhisk"
+ANSIBLE_CMD="ansible-playbook -i ${ROOTDIR}/ansible/environments/local -e docker_image_prefix=openwhisk -e docker_image_tag=nightly"
cd $WHISKDIR/ansible
$ANSIBLE_CMD setup.yml