code: public static void pruneConcurrentScope(PvmExecutionImpl execution) {
      ensureConcurrentScope(execution);
      LOG.debugConcurrentScopeIsPruned(execution);
      execution.setConcurrent(false);
    }
docs: Prunes a concurrent scope. This can only happen if
  (a) the process instance has been migrated from a previous version to a new version of the process engine
  
  This is an inverse operation to {@link #createConcurrentScope(PvmExecutionImpl)}.
  
  See: javadoc of this class for note about concurrent scopes.
  
  @param execution