No module named '_xxsubinterpreters' with Python 3.13.7-1 PostgreSQL 18.1

[markp2]

I am hitting this error:

ERROR: No module named '_xxsubinterpreters'
Traceback (most recent call last):
  File "/home/mark/bootstrap/source/bin/command_line.py", line 579, in main
    dispatch("cmd_", 'subcommand', args)
    ~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/mark/bootstrap/source/bin/command_line.py", line 487, in dispatch
    command(args)
    ~~~~~~~^^^^^^
  File "/home/mark/bootstrap/source/bin/command_line.py", line 129, in cmd_initialise
    import paiyroll_fdw
  File "/home/mark/venv/lib/python3.13/site-packages/paiyroll_fdw/__init__.py", line 27, in <module>
    import multicorn
  File "/home/mark/venv/lib/python3.13/site-packages/multicorn/__init__.py", line 5, in <module>
    from backports import interpreters
  File "/home/mark/venv/lib/python3.13/site-packages/backports/interpreters.py", line 1, in <module>
    import _xxsubinterpreters
ModuleNotFoundError: No module named '_xxsubinterpreters'

This seems to be due to the import statement in python3.13/site-packages/backports/interpreters.py

import _xxsubinterpreters

which is imported by python3.13/site-packages/multicorn/init.py:

import socket
import threading
from wsgiref import simple_server

from backports import interpreters