Fix Bug 2012 use existing volumes as instantiation parameters

RO processes the existing vim-volume-id which is provided through the
instantation parameters, then they are consumed while creating the new VDUs.

Change-Id: Ic3bd71ac7679ab0ccbe9ee0847e4a8d3059c7c58
Signed-off-by: aticig <gulsum.atici@canonical.com>
diff --git a/NG-RO/osm_ng_ro/ns_thread.py b/NG-RO/osm_ng_ro/ns_thread.py
index 8bb8d4b..8cd7d2c 100644
--- a/NG-RO/osm_ng_ro/ns_thread.py
+++ b/NG-RO/osm_ng_ro/ns_thread.py
@@ -415,6 +415,7 @@
 
             return "BUILD", ro_vim_item_update
         except (vimconn.VimConnException, NsWorkerException) as e:
+            self.logger.debug(traceback.format_exc())
             self.logger.error(
                 "task={} {} new-vm: {}".format(task_id, ro_task["target_id"], e)
             )