normalizeHeadTagUrls () {
    if (this.base !== '/' && this.siteConfig.head) {
      this.siteConfig.head.forEach(tag => {
        const attrs = tag[1]
        if (attrs) {
          for (const name in attrs) {
            if (name === 'src' || name === 'href') {
              const value = attrs[name]
              if (value.charAt(0) === '/') {
                attrs[name] = this.base + value.slice(1)
              }
            }
          }
        }
      })
    }
  }
normalize head tag urls for base

@api private