tests/docker: squash initial update and install step for debian9

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

diff --git a/tests/docker/dockerfiles/debian9.docker b/tests/docker/dockerfiles/debian9.docker
index 154ae2a4552f94d3691ea87e75a534bb29e3f685..5f23a35404f24607722569eabb944d887327aec3 100644 (file)
--- a/tests/docker/dockerfiles/debian9.docker
+++ b/tests/docker/dockerfiles/debian9.docker
@@ -13,8 +13,8 @@ FROM debian:stretch-slim
 RUN cat /etc/apt/sources.list | sed "s/^deb\ /deb-src /" >> /etc/apt/sources.list
 
 # Install common build utilities
-RUN apt update
-RUN DEBIAN_FRONTEND=noninteractive apt install -yy eatmydata
+RUN apt-get update && \
+    DEBIAN_FRONTEND=noninteractive apt install -yy eatmydata
 RUN DEBIAN_FRONTEND=noninteractive eatmydata \
     apt install -y --no-install-recommends \
         bison \