At revision 281ab7954d7c, the test_recursionlimit_recovery() test of test_sys is executed at depth 36.

The overflowed flag is reset when the depth becomes smaller than 50 * 3 // 4 = 37, so when Py_LeaveRecursiveCall() is called with depth level 36.

The test raises a RecursionError once which sets the overflowed flag. Then it tries again to raise the RecursionError, but instead Py_FatalError() is called because the overflowed flag was not reset.