Identity on empty account

Seems that #158 (closed) is not fixed anymore.

See https://forum.duniter.org/t/orphaned-identity-on-gt/13198 for example.

Integration test should cover this case: https://git.duniter.org/nodes/rust/duniter-v2s/-/blob/master/runtime/gdev/tests/integration_tests.rs?ref_type=heads#L184