Transient daemons can now be gracefully displaced by foreground or persistent service daemons. The new daemon asks the existing transient daemon to yield, and background workers are re-adopted without interruption. Messages include "yielding to a foreground/service daemon — bg workers will be re-adopted".
Evidence
Daemon yield protocol (search for "yielding to a foreground/service daemon")
Strings lifted out of the shipped bundle, so the claim above can be checked against them.