jenkins: fix bug
@@ -177,6 +177,7 @@ def dockerImages() {
def retainNewestImages(image, n) {
sh """docker images ${image} --format \"{{.Repository}} {{.Tag}}\" \
+| grep -v \"none\" \
| sort -k 2,2 \
| head -n -${n} \
| awk \'BEGIN{OFS=\":\"} {print \$1,\$2}' \
