core: fix selecting of best-default-route to consider only unicast routes

Fixes: 5d0d13f570 ('platform: add support for local routes')

src/nm-ip4-config.h

@@ -83,7 +83,8 @@ nm_ip_config_best_default_route_is (const NMPObject *obj)
 	 * Note that this only considers the main routing table. */
 	return    r
 	       && NM_PLATFORM_IP_ROUTE_IS_DEFAULT (r)
-	       && nm_platform_route_table_is_main (r->table_coerced);
+	       && nm_platform_route_table_is_main (r->table_coerced)
+	       && r->type_coerced == nm_platform_route_type_coerce (1 /*RTN_UNICAST*/);
 }
 
 const NMPObject *_nm_ip_config_best_default_route_find_better (const NMPObject *obj_cur, const NMPObject *obj_cmp);