test_curses does crash on ARM64 Raspbian 3.x buildbot

[vstinner]

Bug report

Bug description:

At build 3000, 3 tests of test_curses failed: https://buildbot.python.org/#/builders/1678/builds/3000

======================================================================
ERROR: test_addch_combining (test.test_curses.TestCurses.test_addch_combining)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/stan/buildarea/3.x.stan-raspbian.nondebug/build/Lib/test/test_curses.py", line 39, in wrapped
    test(self, *args, **kwargs)
    ~~~~^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/stan/buildarea/3.x.stan-raspbian.nondebug/build/Lib/test/test_curses.py", line 261, in test_addch_combining
    stdscr.addch('e\u0301')              # 'e' + COMBINING ACUTE ACCENT
    ~~~~~~~~~~~~^^^^^^^^^^^
ValueError: a character cell must be a single spacing character optionally followed by combining characters

======================================================================
ERROR: test_addch_emoji (test.test_curses.TestCurses.test_addch_emoji)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/stan/buildarea/3.x.stan-raspbian.nondebug/build/Lib/test/test_curses.py", line 39, in wrapped
    test(self, *args, **kwargs)
    ~~~~^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/stan/buildarea/3.x.stan-raspbian.nondebug/build/Lib/test/test_curses.py", line 282, in test_addch_emoji
    stdscr.addch(1, 0, '\u263a\ufe0f')        # WHITE SMILING FACE + VS-16
    ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^
ValueError: a character cell must be a single spacing character optionally followed by combining characters

======================================================================
ERROR: test_wide_characters (test.test_curses.TestCurses.test_wide_characters)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/stan/buildarea/3.x.stan-raspbian.nondebug/build/Lib/test/test_curses.py", line 39, in wrapped
    test(self, *args, **kwargs)
    ~~~~^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/stan/buildarea/3.x.stan-raspbian.nondebug/build/Lib/test/test_curses.py", line 297, in test_wide_characters
    stdscr.echochar(combining)
    ~~~~~~~~~~~~~~~^^^^^^^^^^^
ValueError: a character cell must be a single spacing character optionally followed by combining characters

But now, test_curses does crash: https://buildbot.python.org/#/builders/1678/builds/3089

0:20:03 load avg: 3.12 mem: 56.6 MiB [1/1/1] test_curses worker non-zero exit code (Exit code -11 (SIGSEGV))
Re-running test_curses in verbose mode
test_has_extended_color_support (test.test_curses.MiscTests.test_has_extended_color_support) ... ok
(...)
test_newterm (test.test_curses.ScreenTests.test_newterm) ...

I suppose that these test failures and test crash are caused by recent work on the curses module. cc @serhiy-storchaka

cc @StanFromIreland

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response