Update build

hooks/build

@@ -2,6 +2,6 @@
 # A script to allow building multiple targets from a single Dockerfile such
 # that the repository does not need a separate Dockerfile for each build
 
-export TAG=echo $IMAGE_NAME | sed 's/\(.*\)-a.*/\1/'
+export TAG=$(echo $IMAGE_NAME | sed 's/.*\:\(.*\)-a.*/\1/')
 docker build . -f ${DOCKERFILE_PATH} -t $IMAGE_NAME --build-arg TAG
 docker build . -f ${DOCKERFILE_PATH}-containerized -t $IMAGE_NAME-containerized --build-arg TAG