Change in AdvertiseSecurityKey on httpd side is ignored by running workers

While strengtening the test coverage and tying some loose ends, I encountered the following behaviour. It's always reproducible. Please, take a look at it and comment whether you consider it being a quite evil bug, or whether I'm just being full of ideas

Steps to reproduce

1. Setup Apache HTTP Server balancer with AdvertiseSecurityKey karmYYY and start it.
2. Setup worker 1 with advertise-security-key="karmXXX" and start it.
3. Setup worker 2 with advertise-security-key="karmYYY" and start it.
4. worker 2 talks to balancer, that's cool.
5. worker 1 does not talk to balancer, that's cool.
6. Stop balancer. Keep both workers running.
7. Setup Apache HTTP Server balancer with AdvertiseSecurityKey karmXXX and start it.
8. Now, I would expect that verifyDigest for worker 2 ceases to match and that there will be only worker 1 registered with the balancer. What actually happens is that both worker 1 and worker 2 are registered with the balancer now. STATUS messages are being sent and processed, workers are in OK state.

I took a look at the differences between master and 1.2.10 branch, especially with regard to MODCLUSTER-338 and MODCLUSTER-337, but it bares no connection to this issue. 1.2.10.Final and 1.3.1.Beta1 exhibit the same kind of behaviour.

According to the log, the digest logic is sane, i.e. one gets:

 [org.jboss.modcluster.advertise.impl.AdvertiseListenerImpl] (pool-1-thread-1) Advertise message digest verification failed for server 1a3825d7-e3df-4b5d-9838-52a3756284b0

, but the worker keeps sending STATUS OK messages anyhow.

Would it make sense for the worker to "leave" the balancer if the digest is suddenly not matching?