Stopping only orphaned incumbents had also made a replacement boot give up
when the incumbent's owner was alive, adopting a router whose spawn-only
model list lacks the model just staged (e.g. the desktop downloading while
a CLI owns the server). That case now boots its replacement beside the
live owner's server exactly as before; the only behaviour change left is
that orphans are stopped.
_owner_is_dead had tightened "newer incarnation" to "any create_time
mismatch" for records without start_time. On WSL a stepped clock moves
create_time, so a live owner from an older Hermes could read as dead and
have its server stopped. Those records keep the original comparison.
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