Harness test fails in v.2.10.0: relation is None during removal hook

[sed-i]

  File "/home/ubuntu/code/o11y/traefik-k8s-operator/tests/unit/test_lib_per_unit_requires.py", line 193, in test_ipu_events
    self.harness.remove_relation(self.rel_id)
  File "/home/ubuntu/code/o11y/traefik-k8s-operator/.tox/unit/lib/python3.10/site-packages/ops/testing.py", line 892, in remove_relation
    self._emit_relation_broken(relation_name, relation_id, remote_app)
  File "/home/ubuntu/code/o11y/traefik-k8s-operator/.tox/unit/lib/python3.10/site-packages/ops/testing.py", line 926, in _emit_relation_broken
    self._charm.on[relation_name].relation_broken.emit(relation, app)
  File "/home/ubuntu/code/o11y/traefik-k8s-operator/.tox/unit/lib/python3.10/site-packages/ops/framework.py", line 351, in emit
    framework._emit(event)
  File "/home/ubuntu/code/o11y/traefik-k8s-operator/.tox/unit/lib/python3.10/site-packages/ops/framework.py", line 853, in _emit
    self._reemit(event_path)
  File "/home/ubuntu/code/o11y/traefik-k8s-operator/.tox/unit/lib/python3.10/site-packages/ops/framework.py", line 943, in _reemit
    custom_handler(event)
  File "/home/ubuntu/code/o11y/traefik-k8s-operator/lib/charms/traefik_k8s/v1/ingress_per_unit.py", line 753, in _handle_relation
    self.on.revoked_for_unit.emit(self.relation)  # type: ignore
  File "/home/ubuntu/code/o11y/traefik-k8s-operator/.tox/unit/lib/python3.10/site-packages/ops/framework.py", line 351, in emit
    framework._emit(event)
  File "/home/ubuntu/code/o11y/traefik-k8s-operator/.tox/unit/lib/python3.10/site-packages/ops/framework.py", line 848, in _emit
    self.save_snapshot(event)
  File "/home/ubuntu/code/o11y/traefik-k8s-operator/.tox/unit/lib/python3.10/site-packages/ops/framework.py", line 717, in save_snapshot
    data = value.snapshot()
  File "/home/ubuntu/code/o11y/traefik-k8s-operator/.tox/unit/lib/python3.10/site-packages/ops/charm.py", line 434, in snapshot
    'relation_name': self.relation.name,
AttributeError: 'NoneType' object has no attribute 'name'

Pinning ops < 2.10.0 has the test pass as before.

[sed-i]

Ok I see now that it's after relation broken, so this behavior is desirable and added in #1091.
Closing.