C API: Restore removed PyEval_InitThreads() function

[vstinner]

Since Python 3.7, PyEval_InitThreads() does nothing, since the GIL is now always created: https://vstinner.github.io/python37-gil-change.html This function is deprecated since Python 3.9 and I removed it in Python 3.13 alpha1.

Problem: my Fedora team identified that 16 projects are affected by this function removal.

• collectd
• freeradius
• gnumeric
• libesedb
• libsigrokdecode
• OpenIPMI
• openscap
• profanity
• pyliblo
• pyotherside
• python-confluent-kafka
• python-cradox
• python-gphoto2
• python-simpleaudio
• python-subvertpy
• rb_libtorrent

I propose to restore the function in Python 3.13 beta1, and remove it again in Python 3.14 alpha1.

Linked PRs

• gh-117931

[vstinner]

collectd doesn't seem to be affected for 3 years: https://github.com/collectd/collectd/commit/17d2fbe443b656bb0f74c204eb003cea22f94e60

#if PY_VERSION_HEX < 0x03090000
  // deprecated. Called by Py_Initialize(). Removed in Py3.11
  // https://docs.python.org/3/c-api/init.html#c.PyEval_InitThreads
  PyEval_InitThreads();
#else
  Py_Initialize();
#endif

The problem is that collected 5.12 is affected, there was no release since 2020. Only release candidates of a future 6.0 version.

Fedora bug report: https://bugzilla.redhat.com/show_bug.cgi?id=2247197

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gnumeric was fixed 4 months ago: https://gitlab.gnome.org/GNOME/gnumeric/-/commit/015de3d0df1d59e62e5bfeabab31834082b81196

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pyotherside: I proposed a fix, https://github.com/thp/pyotherside/pull/132/files

[corona10]

python-confluent-kafka: https://github.com/confluentinc/confluent-kafka-python/blob/5a87879681d28375a55203c4839338b13b668046/src/confluent_kafka/src/confluent_kafka.c#L3023-L3025

[vstinner]

Fixed by change https://github.com/python/cpython/commit/75eed5b3734edb221cabb8322d8b8bdf9e3ee6b1