pydantic/pydantic-core mismatch

[Greg Troxel <gdt%lexort.com@localhost>]

Upgrading synapse to 1.143.0 (on 9/2025Q3) results in an exception at
start, which is reproducible (NetBSD 10, pkgsrc HEAD):

  $ python3.13
  Python 3.13.10 (main, Dec  4 2025, 12:19:57) [GCC 10.5.0] on netbsd10
  Type "help", "copyright", "credits" or "license" for more information.
  >>> from pydantic import BaseModel
  Traceback (most recent call last):
    File "<python-input-0>", line 1, in <module>
      from pydantic import BaseModel
    File "/usr/pkg/lib/python3.13/site-packages/pydantic/__init__.py", line 435, in __getattr__
      module = import_module(module_name, package=package)
    File "/usr/pkg/lib/python3.13/importlib/__init__.py", line 88, in import_module
      return _bootstrap._gcd_import(name[level:], package, level)
             ~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/usr/pkg/lib/python3.13/site-packages/pydantic/main.py", line 36, in <module>
      from ._internal import (
      ...<11 lines>...
      )
    File "/usr/pkg/lib/python3.13/site-packages/pydantic/_internal/_decorators.py", line 18, in <module>
      from ._core_utils import get_type_ref
    File "/usr/pkg/lib/python3.13/site-packages/pydantic/_internal/_core_utils.py", line 9, in <module>
      from pydantic_core import validate_core_schema as _validate_core_schema
  ImportError: cannot import name 'validate_core_schema' from 'pydantic_core' (/usr/pkg/lib/python3.13/site-packages/pydantic_core/__init__.py)

The problem is pydantic, basically, in that while 2.11.7's pyproject.toml
says >= 2.33.1, apparently it really is "equal".


Running make test in py-pydantic fails immediately (well, after it
installs 26 test dependencies!):

  ===> Testing for py313-pydantic-2.11.7
  /bin/rm -f /tmp/work/devel/py-pydantic/work/pydantic-2.11.7/tests/test_docs.py /tmp/work/devel/py-pydantic/work/pydantic-2.11.7/tests/test_pickle.py
  ImportError while loading conftest '/tmp/work/devel/py-pydantic/work/pydantic-2.11.7/tests/conftest.py'.
  tests/conftest.py:21: in <module>
      from pydantic._internal._generate_schema import GenerateSchema
  pydantic/_internal/_generate_schema.py:62: in <module>
      from ..functional_validators import AfterValidator, BeforeValidator, FieldValidatorModes, PlainValidator, WrapValidator
  pydantic/functional_validators.py:15: in <module>
      from ._internal import _decorators, _generics, _internal_dataclass
  pydantic/_internal/_decorators.py:18: in <module>
      from ._core_utils import get_type_ref
  pydantic/_internal/_core_utils.py:9: in <module>
      from pydantic_core import validate_core_schema as _validate_core_schema
  E   ImportError: cannot import name 'validate_core_schema' from 'pydantic_core' (/usr/pkg/lib/python3.13/site-packages/pydantic_core/__init__.py)
  *** Error code 4



My installed packages:

  -rw-r--r--  1 root  wheel     2095 Oct 15 15:59 py313-pydantic-core-2.35.2
  -rw-r--r--  1 root  wheel    39390 Oct 15 16:20 py313-pydantic-2.11.7

The upstream bug:

  https://github.com/pydantic/pydantic/issues/12189


At this point I lean to:

  downgrade pydantic-core to 1.33.2

because use of pydantic as is seems troubled for many users.
Downgrading is just changing the version and regenerating
distinfo/crates, as simple as it gets with rust.

Maya: ok to downgrade, or would you like another approach?

Post branch, we probably should upgrade pydantic and pydantic core both
to the latest (minding the dependency in pyproject.toml which is likely
more careful now).