Don't start response until after we add async timeout listener #2106
It is an error to add an async context listener after a context is completed. We need to install the timeout listener before we race against the response.
The unit test passed before the fix, but shows that we don't break the basic functionality. The error condition is rendered on an asynchronous, container owned thread, and I don't see that we have access to it. Furthermore, it only happens under load.