Same as https://github.com/facebook/react/issues/10103, but for the server renderer. You can look at implementation in https://github.com/facebook/react/pull/11168 and do something very similar in `ReactPartialRenderer.js`.
partialState =
              typeof partial === 'function'
                ? partial.call(inst, nextState, element.props, publicContext)
                : partial;
            if (partialState) {
              if (dontMutate) {
                dontMutate = false;
                nextState = Object.assign({}, nextState, partialState);
              } else {
                Object.assign(nextState, partialState);
              }
            }
          }
          inst.state = nextState;
        }
      } else {
        queue = null;
      }
    }
    child = inst.render();
    if (__DEV__) {
      if (child === undefined && inst.render._isMockFunction) {
        
        
        child = null;
      }
    }
    validateRenderResult(child, Component);
    if (typeof inst.getChildContext === 'function') {
      childContextTypes = Component.childContextTypes;