Bump cheroot from 8.5.2 to 8.6.0 (#1603)

* Bump cheroot from 8.5.2 to 8.6.0

Bumps [cheroot](https://github.com/cherrypy/cheroot) from 8.5.2 to 8.6.0.
- [Release notes](https://github.com/cherrypy/cheroot/releases)
- [Changelog](https://github.com/cherrypy/cheroot/blob/master/CHANGES.rst)
- [Commits](https://github.com/cherrypy/cheroot/compare/v8.5.2...v8.6.0)

---
updated-dependencies:
- dependency-name: cheroot
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

* Update cheroot==8.6.0

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: JonnyWong16 <9099342+JonnyWong16@users.noreply.github.com>

lib/cheroot/test/test_wsgi.py

@@ -1,6 +1,7 @@
 """Test wsgi."""
 
 from concurrent.futures.thread import ThreadPoolExecutor
+from traceback import print_tb
 
 import pytest
 import portend
@@ -20,7 +21,7 @@ def simple_wsgi_server():
     """Fucking simple wsgi server fixture (duh)."""
     port = portend.find_available_local_port()
 
-    def app(environ, start_response):
+    def app(_environ, start_response):
         status = '200 OK'
         response_headers = [('Content-type', 'text/plain')]
         start_response(status, response_headers)
@@ -29,7 +30,9 @@ def simple_wsgi_server():
     host = '::'
     addr = host, port
     server = wsgi.Server(addr, app, timeout=600 if IS_SLOW_ENV else 20)
+    # pylint: disable=possibly-unused-variable
     url = 'http://localhost:{port}/'.format(**locals())
+    # pylint: disable=possibly-unused-variable
     with server._run_in_thread() as thread:
         yield locals()
 
@@ -46,6 +49,7 @@ def test_connection_keepalive(simple_wsgi_server):
         with ExceptionTrap(requests.exceptions.ConnectionError) as trap:
             resp = session.get('info')
             resp.raise_for_status()
+        print_tb(trap.tb)
         return bool(trap)
 
     with ThreadPoolExecutor(max_workers=10 if IS_SLOW_ENV else 50) as pool:
@@ -56,3 +60,24 @@ def test_connection_keepalive(simple_wsgi_server):
         failures = sum(task.result() for task in tasks)
 
     assert not failures
+
+
+def test_gateway_start_response_called_twice(monkeypatch):
+    """Verify that repeat calls of ``Gateway.start_response()`` fail."""
+    monkeypatch.setattr(wsgi.Gateway, 'get_environ', lambda self: {})
+    wsgi_gateway = wsgi.Gateway(None)
+    wsgi_gateway.started_response = True
+
+    err_msg = '^WSGI start_response called a second time with no exc_info.$'
+    with pytest.raises(RuntimeError, match=err_msg):
+        wsgi_gateway.start_response('200', (), None)
+
+
+def test_gateway_write_needs_start_response_called_before(monkeypatch):
+    """Check that calling ``Gateway.write()`` needs started response."""
+    monkeypatch.setattr(wsgi.Gateway, 'get_environ', lambda self: {})
+    wsgi_gateway = wsgi.Gateway(None)
+
+    err_msg = '^WSGI write called before start_response.$'
+    with pytest.raises(RuntimeError, match=err_msg):
+        wsgi_gateway.write(None)  # The actual arg value is unimportant