Fix shellcheck complaints

.gitlab-ci.yml

@@ -16,6 +16,5 @@ pylint:
 shellcheck:
   stage: test
   image: it4innovations/docker-shellcheck:latest
-  allow_failure: true
   script:
   - shellcheck *.sh

get_modules.sh

@@ -2,7 +2,7 @@
 # vim: ai ts=2 sw=2 et sts=2 ft=sh
 
 PWD="/home/easybuild/git/it4i-modules"
-cd $PWD
+cd $PWD || exit 1
 
 STATE=$(git fetch 2>&1 | grep master)
 if [ ! -z "$STATE" ]; then
@@ -11,7 +11,7 @@ if [ ! -z "$STATE" ]; then
   exit 0
 fi
 
-CLUSTER=$(echo "$CLUSTERNAME")
+CLUSTER="$CLUSTERNAME"
 if [ -z "$CLUSTER" ]; then
    echo "CLUSTERNAME not defined"
    exit 1