Vue select issue

HTML

<script src="https://rawgit.com/yyx990803/vue/master/dist/vue.js"></script>
<div id="app">
  <select v-model="first">
    <option value="0">option0</option>
    <option value="1" selected>option1</option>
  </select>
</div>

<pre id="console-log"></pre>

JavaScript

function newLog(oldLog) {
  return function() {
    var args = Array.prototype.slice.call(arguments, 0);
    document.getElementById('console-log').innerText += args.join(" ") + "\n";
    oldLog.apply(this, args)
  }
}
console.log = newLog(console.log)
console.error = newLog(console.error)


var application = new Vue({
  el: "#app",
  data: {
    first: "0"
  }
});