RPM: update docker build script

redhat/docker/build.sh

@@ -22,3 +22,9 @@ else
   echo "Saving image to '${FILE}'"
   ${DOCKER} image save "${IMAGE}" | pigz >"${FILE}"
 fi
+
+# Strip 'localhost/' prefix from image tag
+if ! docker images | while read name tag blah; do echo "${name}:${tag}"; done | grep -q "^${IMAGE}$"; then
+  docker image tag "localhost/${IMAGE}" "${IMAGE}"
+  docker image remove "localhost/${IMAGE}"
+fi