Fix bug 1929 for EPA_04 test (exception management error)

Change-Id: I3e75de24a12b7fc88ee63f68dfea0c6c87877905
Signed-off-by: gallardo <sgallardor@indra.es>
diff --git a/RO-SDN-onos_vpls/osm_rosdn_onos_vpls/sdn_assist_onos_vpls.py b/RO-SDN-onos_vpls/osm_rosdn_onos_vpls/sdn_assist_onos_vpls.py
index fa22f10..c02ee15 100644
--- a/RO-SDN-onos_vpls/osm_rosdn_onos_vpls/sdn_assist_onos_vpls.py
+++ b/RO-SDN-onos_vpls/osm_rosdn_onos_vpls/sdn_assist_onos_vpls.py
@@ -241,8 +241,10 @@
             # try to rollback push original config
             try:
                 self._post_onos_netconfig(onos_config_orig)
-            except Exception as e:
-                self.logger.error("Exception rolling back to original config: %s", e)
+            except Exception as rollback_e:
+                self.logger.error(
+                    "Exception rolling back to original config: %s", rollback_e
+                )
 
             # raise exception
             if isinstance(e, SdnConnectorError):