React 0.14.7: `<option value="">empty</option>` emits empty string on change
http://jsbin.com/pisita/10/edit?html,js,console,output
React 15.0.0-rc.1`<option value="">empty</option>` emits string with value "empty" on change
http://jsbin.com/bemaze/12/edit?html,js,console,output
This is because React 15.0.0-rc.1 cuts off `value=""` from option tag

if (propValue == null) {
        continue;
      }
      if (registrationNameModules.hasOwnProperty(propKey)) {
        if (propValue) {
          enqueuePutListener(this, propKey, propValue, transaction);
        }
      } else {
        if (propKey === STYLE) {
          if (propValue) {
            if (__DEV__) {
              
              this._previousStyle = propValue;
            }
            propValue = this._previousStyleCopy = Object.assign({}, props.style);
          }
          propValue = CSSPropertyOperations.createMarkupForStyles(propValue, this);
        }
        var markup = null;
        if (this._tag != null && isCustomComponent(this._tag, props)) {
          if (!RESERVED_PROPS.hasOwnProperty(propKey)) {
            markup = DOMPropertyOperations.createMarkupForCustomAttribute(propKey, propValue);
          }
        } else {
          markup = DOMPropertyOperations.createMarkupForProperty(propKey, propValue);
        }
        if (markup) {
          ret += ' ' + markup;
        }
      }