mercurial fails to build with Python 3.12.0a5.

mercurial/cext/dirs.c -o build/temp.linux-x86_64-cpython-312/mercurial/cext/dirs.o
mercurial/cext/dirs.c: In function '_addpath':
mercurial/cext/dirs.c:16:44: error: 'PyLongObject' {aka 'struct _longobject'} has no member named 'ob_digit'
   16 | #define PYLONG_VALUE(o) ((PyLongObject *)o)->ob_digit[0]
      |                                            ^~
mercurial/cext/dirs.c:93:25: note: in expansion of macro 'PYLONG_VALUE'
   93 |                         PYLONG_VALUE(val) += 1;
      |                         ^~~~~~~~~~~~
mercurial/cext/dirs.c:16:44: error: 'PyLongObject' {aka 'struct _longobject'} has no member named 'ob_digit'
   16 | #define PYLONG_VALUE(o) ((PyLongObject *)o)->ob_digit[0]
      |                                            ^~
mercurial/cext/dirs.c:104:17: note: in expansion of macro 'PYLONG_VALUE'
  104 |                 PYLONG_VALUE(val) = 1;
      |                 ^~~~~~~~~~~~
mercurial/cext/dirs.c: In function '_delpath':
mercurial/cext/dirs.c:16:44: error: 'PyLongObject' {aka 'struct _longobject'} has no member named 'ob_digit'
   16 | #define PYLONG_VALUE(o) ((PyLongObject *)o)->ob_digit[0]
      |                                            ^~
mercurial/cext/dirs.c:141:23: note: in expansion of macro 'PYLONG_VALUE'
  141 |                 if (--PYLONG_VALUE(val) <= 0) {
      |                       ^~~~~~~~~~~~

GH-101291: Refactor the PyLongObject struct #101292
https://github.com/python/cpython/pull/101292
https://docs.python.org/3.12/whatsnew/3.12.html

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.12/fedora-rawhide-x86_64/05586681-mercurial/

For all our attempts to build mercurial with Python 3.12, see:
https://copr.fedorainfracloud.org/coprs/g/python/python3.12/package/mercurial/

Testing and mass rebuild of packages is happening in copr. You can follow these instructions to test locally in mock if your package builds with Python 3.12:
https://copr.fedorainfracloud.org/coprs/g/python/python3.12/

Let us know here if you have any questions.

Python 3.12 is planned to be included in Fedora 39. To make that update smoother, we're building Fedora packages with all pre-releases of Python 3.12.
A build failure prevents us from testing all dependent packages (transitive [Build]Requires), so if this package is required a lot, it's important for us to get it fixed soon.
We'd appreciate help from the people who know this package best, but if you don't want to work on this now, let us know so we can try to work around it on our side.