try to fix at_exit_once

Author: Carreau

tests/conftest.py

@@ -225,7 +225,7 @@ async def ipkernel(anyio_backend):
             yield kernel
         finally:
             kernel.destroy()
-            kernel.shell.history_manager = None
+            kernel.shell._atexit_once()
             kernel.shell.configurables = []
             ZMQInteractiveShell.clear_instance()
 

tests/test_zmq_shell.py

@@ -233,7 +233,7 @@ def test_magics(tmp_path):
         socket.close()
         context.destroy()
     finally:
-        shell.history_manager = None
+        shell._atexit_once()
         shell.configurables = []
         InteractiveShell.clear_instance()
 
@@ -258,7 +258,7 @@ def test_zmq_interactive_shell(kernel):
             shell.system_piped("dir")
         shell.ask_exit()
     finally:
-        shell.history_manager = None
+        shell._atexit_once()
         shell.configurables = []
         ZMQInteractiveShell.clear_instance()