Segfault with Python 3.13.0b1

[mgorny]

$ export CFLAGS='-Og -g -Wall'
$ python3.13 setup.py build_ext -i
running build_ext
building 'immutables._map' extension
creating build
creating build/temp.linux-x86_64-cpython-313
creating build/temp.linux-x86_64-cpython-313/immutables
x86_64-pc-linux-gnu-gcc -fno-strict-overflow -Wsign-compare -Og -g -Wall -fPIC -DNDEBUG=1 -I/usr/include/python3.13 -c immutables/_map.c -o build/temp.linux-x86_64-cpython-313/immutables/_map.o -O2 -std=c99 -fsigned-char -Wall -Wsign-compare -Wconversion
immutables/_map.c: In function ‘map_node_bitmap_dump’:
immutables/_map.c:1287:12: warning: implicit declaration of function ‘_PyLong_Format’; did you mean ‘_PyLong_Copy’? [-Wimplicit-function-declaration]
 1287 |     tmp2 = _PyLong_Format(tmp1, 2);
      |            ^~~~~~~~~~~~~~
      |            _PyLong_Copy
immutables/_map.c:1287:10: warning: assignment to ‘PyObject *’ {aka ‘struct _object *’} from ‘int’ makes pointer from integer without a cast [-Wint-conversion]
 1287 |     tmp2 = _PyLong_Format(tmp1, 2);
      |          ^
creating build/lib.linux-x86_64-cpython-313
creating build/lib.linux-x86_64-cpython-313/immutables
x86_64-pc-linux-gnu-gcc -shared -Og -g -Wall build/temp.linux-x86_64-cpython-313/immutables/_map.o -L/usr/lib64 -o build/lib.linux-x86_64-cpython-313/immutables/_map.cpython-313-x86_64-linux-gnu.so
copying build/lib.linux-x86_64-cpython-313/immutables/_map.cpython-313-x86_64-linux-gnu.so -> immutables
$ python -m pytest -s
========================================================= test session starts =========================================================
platform linux -- Python 3.13.0b1, pytest-8.2.0, pluggy-1.5.0
rootdir: /tmp/immutables
configfile: pyproject.toml
testpaths: tests
collected 159 items                                                                                                                   

tests/test_issue24.py .....Fatal Python error: Segmentation fault

Current thread 0x00007f08dab04740 (most recent call first):
  File "/tmp/immutables/tests/test_issue24.py", line 121 in hamt_dump_check_first_return_second
  File "/tmp/immutables/tests/test_issue24.py", line 141 in test_array_node_delete_in_place_count
  File "/usr/lib/python3.13/unittest/case.py", line 606 in _callTestMethod
  File "/usr/lib/python3.13/unittest/case.py", line 651 in run
  File "/usr/lib/python3.13/unittest/case.py", line 707 in __call__
  File "/tmp/venv/lib/python3.13/site-packages/_pytest/unittest.py", line 343 in runtest
  File "/tmp/venv/lib/python3.13/site-packages/_pytest/runner.py", line 173 in pytest_runtest_call
  File "/tmp/venv/lib/python3.13/site-packages/pluggy/_callers.py", line 103 in _multicall
  File "/tmp/venv/lib/python3.13/site-packages/pluggy/_manager.py", line 120 in _hookexec
  File "/tmp/venv/lib/python3.13/site-packages/pluggy/_hooks.py", line 513 in __call__
  File "/tmp/venv/lib/python3.13/site-packages/_pytest/runner.py", line 241 in <lambda>
  File "/tmp/venv/lib/python3.13/site-packages/_pytest/runner.py", line 341 in from_call
  File "/tmp/venv/lib/python3.13/site-packages/_pytest/runner.py", line 240 in call_and_report
  File "/tmp/venv/lib/python3.13/site-packages/_pytest/runner.py", line 135 in runtestprotocol
  File "/tmp/venv/lib/python3.13/site-packages/_pytest/runner.py", line 116 in pytest_runtest_protocol
  File "/tmp/venv/lib/python3.13/site-packages/pluggy/_callers.py", line 103 in _multicall
  File "/tmp/venv/lib/python3.13/site-packages/pluggy/_manager.py", line 120 in _hookexec
  File "/tmp/venv/lib/python3.13/site-packages/pluggy/_hooks.py", line 513 in __call__
  File "/tmp/venv/lib/python3.13/site-packages/_pytest/main.py", line 364 in pytest_runtestloop
  File "/tmp/venv/lib/python3.13/site-packages/pluggy/_callers.py", line 103 in _multicall
  File "/tmp/venv/lib/python3.13/site-packages/pluggy/_manager.py", line 120 in _hookexec
  File "/tmp/venv/lib/python3.13/site-packages/pluggy/_hooks.py", line 513 in __call__
  File "/tmp/venv/lib/python3.13/site-packages/_pytest/main.py", line 339 in _main
  File "/tmp/venv/lib/python3.13/site-packages/_pytest/main.py", line 285 in wrap_session
  File "/tmp/venv/lib/python3.13/site-packages/_pytest/main.py", line 332 in pytest_cmdline_main
  File "/tmp/venv/lib/python3.13/site-packages/pluggy/_callers.py", line 103 in _multicall
  File "/tmp/venv/lib/python3.13/site-packages/pluggy/_manager.py", line 120 in _hookexec
  File "/tmp/venv/lib/python3.13/site-packages/pluggy/_hooks.py", line 513 in __call__
  File "/tmp/venv/lib/python3.13/site-packages/_pytest/config/__init__.py", line 178 in main
  File "/tmp/venv/lib/python3.13/site-packages/_pytest/config/__init__.py", line 206 in console_main
  File "/tmp/venv/lib/python3.13/site-packages/pytest/__main__.py", line 7 in <module>
  File "<frozen runpy>", line 88 in _run_code
  File "<frozen runpy>", line 198 in _run_module_as_main
Segmentation fault (core dumped)
$ coredumpctl gdb -1
[…]
#0  0x00007f08da29d2bc in ?? () from /usr/lib64/libc.so.6
#1  0x00007f08da24b926 in raise () from /usr/lib64/libc.so.6
#2  <signal handler called>
#3  0x00007f08da5f3a11 in PyObject_Str () from /usr/lib64/libpython3.13.so.1.0
#4  0x00007f08da5a6faf in PyUnicode_FromFormatV () from /usr/lib64/libpython3.13.so.1.0
#5  0x00007f08d8df7ef2 in _map_dump_format (writer=writer@entry=0x7ffe833cc340, 
    format=format@entry=0x7f08d8dfd03e "bitmap=%S id=%p):\n") at immutables/_map.c:537
#6  0x00007f08d8df8e44 in map_node_bitmap_dump (level=1, writer=0x7ffe833cc340, node=0x7f08d758cdb0) at immutables/_map.c:1292
#7  map_node_dump (node=0x7f08d758cdb0, writer=writer@entry=0x7ffe833cc340, level=level@entry=1) at immutables/_map.c:2261
#8  0x00007f08d8df8d71 in map_node_array_dump (level=0, writer=0x7ffe833cc340, node=0x7f08d7d4f480) at immutables/_map.c:2127
#9  map_node_dump (node=0x7f08d7d4f480, writer=writer@entry=0x7ffe833cc340, level=level@entry=0) at immutables/_map.c:2265
#10 0x00007f08d8df8f9f in map_dump (self=0x7f08d7563140) at immutables/_map.c:2620
#11 map_py_dump (self=0x7f08d7563140, args=<optimized out>) at immutables/_map.c:3191
#12 0x00007f08da5ddf97 in ?? () from /usr/lib64/libpython3.13.so.1.0
#13 0x00007f08da5a51b5 in PyObject_Vectorcall () from /usr/lib64/libpython3.13.so.1.0
#14 0x00007f08da5bb637 in _PyEval_EvalFrameDefault () from /usr/lib64/libpython3.13.so.1.0
#15 0x00007f08da601f66 in ?? () from /usr/lib64/libpython3.13.so.1.0
#16 0x00007f08da5f0427 in ?? () from /usr/lib64/libpython3.13.so.1.0
#17 0x00007f08da5bd27e in _PyEval_EvalFrameDefault () from /usr/lib64/libpython3.13.so.1.0
#18 0x00007f08da5a5dea in ?? () from /usr/lib64/libpython3.13.so.1.0
#19 0x00007f08da5e7301 in ?? () from /usr/lib64/libpython3.13.so.1.0
#20 0x00007f08da6ac8f3 in ?? () from /usr/lib64/libpython3.13.so.1.0
#21 0x00007f08da5a0db4 in _PyObject_MakeTpCall () from /usr/lib64/libpython3.13.so.1.0
#22 0x00007f08da5c3963 in _PyEval_EvalFrameDefault () from /usr/lib64/libpython3.13.so.1.0
#23 0x00007f08da5a5dea in ?? () from /usr/lib64/libpython3.13.so.1.0
#24 0x00007f08da5e7301 in ?? () from /usr/lib64/libpython3.13.so.1.0
#25 0x00007f08da6ac8f3 in ?? () from /usr/lib64/libpython3.13.so.1.0
#26 0x00007f08da5f0289 in ?? () from /usr/lib64/libpython3.13.so.1.0
#27 0x00007f08da5bd27e in _PyEval_EvalFrameDefault () from /usr/lib64/libpython3.13.so.1.0
#28 0x00007f08da5a5dea in ?? () from /usr/lib64/libpython3.13.so.1.0
#29 0x00007f08da5e7301 in ?? () from /usr/lib64/libpython3.13.so.1.0
#30 0x00007f08da6ac8f3 in ?? () from /usr/lib64/libpython3.13.so.1.0
#31 0x00007f08da5a0db4 in _PyObject_MakeTpCall () from /usr/lib64/libpython3.13.so.1.0
#32 0x00007f08da5c3963 in _PyEval_EvalFrameDefault () from /usr/lib64/libpython3.13.so.1.0
#33 0x00007f08da5a5dea in ?? () from /usr/lib64/libpython3.13.so.1.0
#34 0x00007f08da5e7301 in ?? () from /usr/lib64/libpython3.13.so.1.0
#35 0x00007f08da6ac8f3 in ?? () from /usr/lib64/libpython3.13.so.1.0
#36 0x00007f08da5a0db4 in _PyObject_MakeTpCall () from /usr/lib64/libpython3.13.so.1.0
#37 0x00007f08da5c3963 in _PyEval_EvalFrameDefault () from /usr/lib64/libpython3.13.so.1.0
#38 0x00007f08da5a5dea in ?? () from /usr/lib64/libpython3.13.so.1.0
#39 0x00007f08da5e7301 in ?? () from /usr/lib64/libpython3.13.so.1.0
#40 0x00007f08da6ac8f3 in ?? () from /usr/lib64/libpython3.13.so.1.0
#41 0x00007f08da5a0db4 in _PyObject_MakeTpCall () from /usr/lib64/libpython3.13.so.1.0
#42 0x00007f08da5c3963 in _PyEval_EvalFrameDefault () from /usr/lib64/libpython3.13.so.1.0
#43 0x00007f08da6590ad in PyEval_EvalCode () from /usr/lib64/libpython3.13.so.1.0
#44 0x00007f08da67469b in ?? () from /usr/lib64/libpython3.13.so.1.0
#45 0x00007f08da5cfcc6 in ?? () from /usr/lib64/libpython3.13.so.1.0
#46 0x00007f08da5a51b5 in PyObject_Vectorcall () from /usr/lib64/libpython3.13.so.1.0
#47 0x00007f08da5bb637 in _PyEval_EvalFrameDefault () from /usr/lib64/libpython3.13.so.1.0
#48 0x00007f08da68e1ec in ?? () from /usr/lib64/libpython3.13.so.1.0
#49 0x00007f08da68d9a3 in Py_RunMain () from /usr/lib64/libpython3.13.so.1.0
#50 0x00007f08da6411bb in Py_BytesMain () from /usr/lib64/libpython3.13.so.1.0
#51 0x00007f08da235350 in ?? () from /usr/lib64/libc.so.6
#52 0x00007f08da235409 in __libc_start_main () from /usr/lib64/libc.so.6
#53 0x0000562f9225b085 in _start ()