[sans-io] enable sans-io by default

mitmproxy/addons/proxyserver.py

@@ -99,7 +99,7 @@ class Proxyserver:
             self.server = await asyncio.start_server(
                 self.handle_connection,
                 self.options.listen_host,
-                self.options.listen_port + 1,
+                self.options.listen_port,
             )
 
     async def shutdown_server(self):

mitmproxy/utils/compat.py

@@ -1,4 +1,4 @@
-new_proxy_core = False
+new_proxy_core = True
 """If true, use mitmproxy's new sans-io proxy core."""
 
 if new_proxy_core:  # pragma: no cover