Handle the case where ONOS_APPS is not defined - needed for Jenkins

Change-Id: I66b08f25ebc9171653ae673ea5c562ecb53bcf8c
diff --git a/tools/dev/bash_profile b/tools/dev/bash_profile
index b47d286..5208643 100644
--- a/tools/dev/bash_profile
+++ b/tools/dev/bash_profile
@@ -241,7 +241,7 @@
         rm -f $aux
         # This is a hack to get master running on the existing cell infrastructure
         apps=${ONOS_APPS:-}
-        export ONOS_APPS=$ONOS_APPS,gui
+        export ONOS_APPS=$apps,gui
         setPrimaryInstance 1 >/dev/null
         setMinorityMajority >/dev/null
         onos-verify-cell