Schema transformer should restore route target list at restart

When schema transformer restarts, it resets route targets to what is currently
applicable. But it is not restoring the primary routing-instance's target as an
export target on service routing instances if needed. With this patch, that is
fixed.

Change-Id: Id829af2e3d16f98b52f2b21a8c9f2fdff21ecde5
Closes-Bug: 1518415

src/config/schema-transformer/to_bgp.py

@@ -514,6 +514,9 @@ def locate_routing_instance(self, rinst_name, service_chain=None,
                         for rt in self.rt_list:
                             rtgt_obj = RouteTarget(rt)
                             rinst_obj.add_route_target(rtgt_obj, inst_tgt_data)
+                        if not is_default and self.allow_transit:
+                            rtgt_obj = RouteTarget(self._route_target)
+                            rinst_obj.add_route_target(rtgt_obj, inst_tgt_data)
                     if (not compare_refs(rinst_obj.get_route_target_refs(),
                                          old_rt_refs)):
                         need_update = True
@@ -529,6 +532,9 @@ def locate_routing_instance(self, rinst_name, service_chain=None,
                     for rt in self.rt_list:
                         rtgt_obj = RouteTarget(rt)
                         rinst_obj.add_route_target(rtgt_obj, inst_tgt_data)
+                    if not is_default and self.allow_transit:
+                        rtgt_obj = RouteTarget(self._route_target)
+                        rinst_obj.add_route_target(rtgt_obj, inst_tgt_data)
                 _vnc_lib.routing_instance_create(rinst_obj)
         except (BadRequest, HttpError) as e:
             _sandesh._logger.error(