bug fix: give both tags to `docker tag` (#186)

diff --git a/tools/travis/deploy.sh b/tools/travis/deploy.sh
index 007e244..9f1389d 100755
--- a/tools/travis/deploy.sh
+++ b/tools/travis/deploy.sh
@@ -37,7 +37,7 @@
   dockerhub_githash_image="${dockerhub_image_prefix}/${dockerhub_image_name}:${short_commit}"
 
   echo docker tag ${dockerhub_image} ${dockerhub_githash_image}
-  docker tag ${dockerhub_githash_image}
+  docker tag ${dockerhub_image} ${dockerhub_githash_image}
 
   echo docker push ${dockerhub_githash_image}
   docker push ${dockerhub_githash_image}