[Vue warn]:Attribute "is" is ignored on component <tr> because the component is a fragment instance

`[Vue warn]:Attribute "is" is ignored on component <tr> because the component is a fragment instance: http://vuejs.org/guide/components.html#Fragment_Instance`

1.0.6使用vue-router的情况下，直接刷新不会出现这个错误，再点击其它链接的时候就会出现这个提示。1.0.3无此问题。
tr定义如下：

```
<tr is="row" v-for="row in list | filterBy filterKey in fields| orderBy sortKey sortOrders[sortKey]"
            :row="row" :index="$index"></tr>
```
