Bug in composition-api beta 14

[zippaaa]

composition-api beta 12

<template>
  <div>
        <p v-for="item in items">
            {{ item }}
        </p>
  </div>
</template>

export default {
    setup(props, { root }) {
        const items = reactive([]);
        setTimeout(() => {
            items.push(...['a', 'b', 'c']);
        }, 5000);
    }
}

Result:

a
b
c

composition-api beta 14
nothing