[Exim] Fallback hosts change in Exim 4.31

Hi,

I'm curious about change #21 in Exim 4.31 regarding fallback_hosts and
ultimate retry timeouts:

  21. If all the "regular" hosts to which an address was routed had passed
      their expiry times, and had not reached their retry times, the address
      was bounced, even if fallback hosts were defined. Now Exim should go
      on to try the fallback hosts.

My understanding is that fallback_hosts is a transport option, even though
it can be specified on a router to pass on to the transport.

Does this change also affect long retry failures on DNS lookup
failures at the routing level? Or does the change only affect long
retry failures at the transport level?

--
Dean Brooks
dean@???