Clear exception flag on disconnect future if its also sent to handlers

If we do not clear the exception retrieved flag on the disconnect
future it will likely never be retrieved since wait_for_disconnect
will never be called when the reply handler raises.

src/dbus_fast/aio/message_bus.py

@@ -1,5 +1,6 @@
 import array
 import asyncio
+import contextlib
 import logging
 import socket
 from collections import deque
@@ -522,13 +523,23 @@ def _finalize(self, err: Optional[Exception] = None) -> None:
         except Exception:
             logging.warning("could not remove message writer", exc_info=True)
 
+        had_handlers = bool(self._method_return_handlers or self._user_message_handlers)
+
         super()._finalize(err)
 
         if self._disconnect_future.done():
             return
 
         if err and not self._user_disconnect:
             _future_set_exception(self._disconnect_future, err)
+            # If this happens during a reply the message handlers
+            # will have the exception set and wait_for_disconnect will
+            # never be called so we need to manually set the exception
+            # as retrieved to avoid asyncio warnings when the future
+            # is garbage collected.
+            if had_handlers:
+                with contextlib.suppress(Exception):
+                    self._disconnect_future.exception()
         else:
             _future_set_result(self._disconnect_future, None)