title: Cancellation token in iis not triggering
body: <p>I have an API with .net core 2.1 and use cancellation tokens in actions. When i run the project with iis and make a simple request in browser, after i cancel it, it doesn't work as expected and run all methods with cancellation token passed to them.
  But when i run the project using the kestrel server, cancelling the request causes the server to work as expected. why is that?  </p>
  
  <pre><code>    [HttpGet("get")]
      public async Task&lt;IActionResult&gt; GetSome(CancellationToken ct)
      {
  
          _logger.LogInformation("The slow Request Start");
          try
          {
              await Task.Delay(10_000, ct);
              _logger.LogCritical("Successful");
          }
          catch (Exception)
          {
              _logger.LogInformation("Task Cancelled");
          }
          var message = "The request finished";
  
          _logger.LogInformation(message);
  
          return NoContent();
      }
  </code></pre>