Remote Execution vs re-built systems

Am I missing something here?

I deployed a client from my Katello 3.3 RC2. I have successfully run
remote commands on this client. I rebuild the client via the "Build"
button on the Host page. I try to run remote commands again, but these
fail due to:

Error initializing command: Net::SSH::HostKeyMismatch - fingerprint
84:2f:bc:c8:79:b8:2e:f8:50:8c:a0:66:39:62:88:d3 does not match for

This particular client is using the same MAC, IP Address, Hostname etc. as
the original.

When I remove the offending (old) key
from /usr/share/foreman-proxy/.ssh/known_hosts the remote execution works

I can understand this being the case, but wondering if I've forgotten to do
something. Shouldn't the old keys be removed from foreman-proxy
known_hosts when the rebuild is executed? Or at the "Informing Foreman
that we are built" stage? Or when the new client registers with Katello?

Haven't tested this against a plain Foreman server, but I would suggest the
behaviour would be the same.

Unless I've done something wrong obviously.