Python ContextVars don't propagate across exception handling boundaries

ctx.py

# coding: utf-8

import contextvars
import sys

v = contextvars.ContextVar('v')
v.set('global default')

def code():
    print(f'before: v={v.get()}')
    v.set('local code')
    print(f'after: v={v.get()}')
    1/0

def wrap_excepthook(old):
    def excepthook(etype, value, traceback):
        print(f'excepthook: v={v.get()}')
        old(etype, value, traceback)
    return excepthook

sys.excepthook = wrap_excepthook(sys.excepthook)

try:
    contextvars.copy_context().run(code)
except Exception as e:
    print(f'exception: v={v.get()}')
    raise e

shell

$ python3 ctx.py
before: v=global default
after: v=local code
exception: v=global default
excepthook: v=global default
Traceback (most recent call last):
  File "/Users/rodolfo/ctx.py", line 27, in <module>
    raise e
  File "/Users/rodolfo/ctx.py", line 24, in <module>
    contextvars.copy_context().run(code)
  File "/Users/rodolfo/ctx.py", line 13, in code
    1/0
ZeroDivisionError: division by zero