Previously we were unsetting ONOS_USER and then checking whether

it was set, which doesn't make sense. The intent seems to be
to set a default and to respect existing settings of ONOS_USER,
and probably ONOS_GROUP as well.

Change-Id: I80dcbc2ccd80791c76b2497fd1da317765a6e66f

@@ -110,9 +110,10 @@ function cell {
         [ ! -f $ONOS_ROOT/tools/test/cells/$1 ] && \
             echo "No such cell: $1" >&2 && return 1
         unset ONOS_CELL ONOS_NIC ONOS_IP ONOS_APPS ONOS_BOOT_FEATURES
-        unset OCI OCN OCT ONOS_INSTANCES ONOS_USER ONOS_GROUP ONOS_FEATURES
+        unset OCI OCN OCT ONOS_INSTANCES ONOS_FEATURES ONOS_USER ONOS_GROUP
         unset $(env | sed -n 's:\(^OC[0-9]\{1,\}\)=.*:\1 :g p')
         export ONOS_USER=${ONOS_USER:-sdn}
+        export ONOS_GROUP=${ONOS_GROUP:-sdn}
         export ONOS_WEB_USER=onos
         export ONOS_WEB_PASS=rocks
         export ONOS_CELL=$1