The queue-full test used an empty queue, so a reliable refusal fitted and
the reliable-refusal mutant lived. The new test fills a queue of 8
exactly with a reply the peer never acknowledges; the next reply cannot
be queued, and its refusal must still arrive, acknowledging nothing the
peer sent. A RawPeer helper drives the peer packet by packet; the gap
test uses it too.
A response too large for any datagram fails with the kernel's EMSGSIZE:
the rejection is ResponseSendFailed("EMSGSIZE"), the goodbye is exactly
"packet could not be sent: EMSGSIZE", and no refusal is sent.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>