update docker build script to use latest bionic. (#269)

diff --git a/tools/make_docker_image b/tools/make_docker_image
index 0559934c02b7136e6fa10f461b5b7e2fb65df926..ff4f9801649789f7f98f79a7351bf824c43de962 100755 (executable)
--- a/tools/make_docker_image
+++ b/tools/make_docker_image
@@ -1,7 +1,7 @@
-#!/bin/bash -e
+#!/bin/bash -ex
 # you must be logged into docker for the push to succeed.
 tag=$(date -u +%Y%m%dT%H%M%SZ)
-docker build -t gpsbabel_build_environment:latest .
+docker build --pull --tag gpsbabel_build_environment:latest .
 docker tag gpsbabel_build_environment:latest gpsbabel_build_environment:$tag
 docker tag gpsbabel_build_environment:latest tsteven4/gpsbabel_build_environment:latest 
 docker tag gpsbabel_build_environment:latest tsteven4/gpsbabel_build_environment:$tag