gh-133548: fix handling of empty and 1-item tuples for sys.exit

Doc/whatsnew/3.15.rst

@@ -78,6 +78,11 @@ Other language changes
 * Several error messages incorrectly using the term "argument" have been corrected.
   (Contributed by Stan Ulbrych in :gh:`133382`.)
 
+* :func:`sys.exit` and :exc:`SystemExit` now correctly handle empty and 1-item
+  tuples arguments. Previously, such tuples were unpacked by :func:`!sys.exit`
+  but not by :exc:`!SystemExit` and the process status code was incorrectly
+  set.
+  (Contributed by Bénédikt Tran in :gh:`133548`.)
 
 
 New modules

Python/sysmodule.c

@@ -917,7 +917,8 @@ sys_exit_impl(PyObject *module, PyObject *status)
 {
     /* Raise SystemExit so callers may catch it or clean up. */
     if (PyTuple_Check(status)) {
-        /* Make sure that tuples are not flattened during normalization. */
+        /* Make sure that tuples are not flattened during normalization
+         * due to the fast path for tuples in _PyErr_CreateException(). */
         PyObject *exc = PyObject_CallOneArg(PyExc_SystemExit, status);
         PyErr_SetObject(PyExc_SystemExit, exc);
         Py_DECREF(exc);