VOL-2719 Run library sanity tests as nightly jobs

Change-Id: I7a6c9fa5a764bd3fbff06f994a41cbde835a05fa
diff --git a/jjb/pipeline/voltha-bbsim-tests.groovy b/jjb/pipeline/voltha-bbsim-tests.groovy
index b1a7413..6363770 100644
--- a/jjb/pipeline/voltha-bbsim-tests.groovy
+++ b/jjb/pipeline/voltha-bbsim-tests.groovy
@@ -64,7 +64,12 @@
       steps {
         sh """
            pushd voltha
-           repo download "${gerritProject}" "${gerritChangeNumber}/${gerritPatchsetNumber}"
+           if [ "${gerritProject}" != "" -a "${gerritChangeNumber}" != "" -a "${gerritPatchsetNumber}" != "" ]
+           then
+             repo download "${gerritProject}" "${gerritChangeNumber}/${gerritPatchsetNumber}"
+           else
+             echo "No patchset to download!"
+           fi
            popd
            """
       }