Syntax fixes.

Change-Id: I4809f8a429f12161a1b65cd848513aa6ffdbc2fb
diff --git a/cicd/pipelines/tasks/task_publish_unstable.jenkins b/cicd/pipelines/tasks/task_publish_unstable.jenkins
index e0c21c2..a3feb08 100644
--- a/cicd/pipelines/tasks/task_publish_unstable.jenkins
+++ b/cicd/pipelines/tasks/task_publish_unstable.jenkins
@@ -15,14 +15,14 @@
                                         privileged: true)
 def aptlyVolume = persistentVolumeClaim(claimName: 'aptly-state', mountPath: '/var/lib/aptly')
 
-def getLatestSnapshot(repository_stem) {
+String getLatestSnapshot(repository_stem) {
     def script = """
         aptly snapshot list --sort=time --raw \
             | grep -E '^${repository_stem}-' \
             | head -n1
     """
 
-    return sh returnStdout: true, script: script
+    return sh(returnStdout: true, script: script)
 }
 
 podTemplate(label: buildLabel, containers: [jnlpContainer, debianContainer], volumes: [aptlyVolume], envVars: []) {