Ensure source checks are retried if failed

cpp/ci_database_objs.cpp

@@ -913,6 +913,7 @@ bool PackageConf::can_check_source_upload() {
             }
 
             if (jobstatus->name == "source_check" && task_ptr && !task_ptr->successful) {
+                _successful_task_count--;
                 source_check_timestamp = task_ptr->finish_time;
                 continue;
             }