build-system: fix tag conditional

Refs #55550

Change-Id: Ie5beacded9dd37b83401958202ec24c7511fb444

tools/build-system/launch-build-machine-jenkins.sh

@@ -116,7 +116,7 @@ echo "Update reference sources"
 git checkout . && git checkout -f master && git pull
 
 # Get the version
-if [ -n $TAG ]; then
+if [ -n "$TAG" ]; then
     CURRENT_RELEASE_TAG_NAME="$TAG"
 else
     CURRENT_RELEASE_TAG_NAME=`git describe --tags --abbrev=0`