Automatically enable --stream on server sent events (#1226)

* Automatically enable --stream when used chunked encoding

* try fix 3.6 mock issue

* Only enable on text/event-stream

Co-authored-by: Jakub Roztocil <jakub@roztocil.co>

tests/utils/http_server.py

@@ -36,6 +36,22 @@ def get_headers(handler):
     handler.end_headers()
 
 
+@TestHandler.handler('GET', '/drip')
+def chunked_drip(handler):
+    handler.send_response(200)
+    accept = handler.headers.get('Accept')
+    if accept is not None:
+        handler.send_header('Content-Type', accept)
+    handler.send_header('Transfer-Encoding', 'chunked')
+    handler.end_headers()
+
+    for _ in range(3):
+        body = 'test\n'
+        handler.wfile.write(f'{len(body):X}\r\n{body}\r\n'.encode('utf-8'))
+
+    handler.wfile.write('0\r\n\r\n'.encode('utf-8'))
+
+
 @pytest.fixture(scope="function")
 def http_server():
     """A custom HTTP server implementation for our tests, that is