为什么setAttribute（'href'）在IE中需要两次？

Question

今天我读了axios分数并在'isURLSameOrigin.js'中，我看了一些代码，

(function standardBrowserEnv () {
      var msie = /(msie|trident)/i.test(navigator.userAgent)
      var urlParsingNode = document.createElement('a')
      var originURL

      function resolveURL (url) {
        var href = url
  
        // this is important
        if (msie) {
          urlParsingNode.setAttribute('href', href)
          href = urlParsingNode.href
        }

        urlParsingNode.setAttribute('href', href)

        return {
          href: urlParsingNode.href,
          protocol: urlParsingNode.protocol ? urlParsingNode.protocol.replace(/:$/, '') : '',
          host: urlParsingNode.host,
          search: urlParsingNode.search ? urlParsingNode.search.replace(/^\?/, '') : '',
          hash: urlParsingNode.hash ? urlParsingNode.hash.replace(/^#/, '') : '',
          hostname: urlParsingNode.hostname,
          port: urlParsingNode.port,
          pathname: (urlParsingNode.pathname.charAt(0) === '/')
            ? urlParsingNode.pathname
            : '/' + urlParsingNode.pathname
        }
      }

      originURL = resolveURL(window.location.href)

      return function isURLSameOrigin (requestURL) {
        var parsed = (utils.isString(requestURL)) ? resolveURL(requestURL) : requestURL
        return (parsed.protocol === originURL.protocol &&
            parsed.host === originURL.host)
      }
    })()

它为IE .it setAttribute（'href'，href）做了两次难度。我只是想知道为什么？这很重要，看起来没用。