title: Why there is no std::string::append/insert recivieng rvalue string?
body: <pre><code>basic_string&amp; append(basic_string&amp;&amp; Right) {
      if (Right.capacity() &gt;= size() + Right.size())
      {
          swap(Right);
          insert(0, Right);
          return *this;
      }
      return append(Right); // lvalue reference overload
  }
  </code></pre>
  <p>Is it just lack of committee time or there is some problem with my implementation? <em><code>string::swap</code> is <code>noexcept</code>, assume <code>char_traits::move</code> <code>noexcept</code> too</em></p>