title: What does "Cannot write to closing transport" mean?
body: <p>I get the exception <code>"Cannot write to closing transport"</code> raised from <code>aiohttp.http_writer.StreamWriter#_write</code>, but only  in a fraction of cases.</p>
  
  <p>The relevant snippet.</p>
  
  <pre><code>    session: aiohttp.ClientSession
      async with session.get(url, timeout=60) as response:
          txt = await response.text()
          response.close()
          return txt
  </code></pre>
  
  <p>What is going on? I don't think the server-size is closing the socket.</p>