BIND 9.11.1-P3 revives expired zones briefly during reconfig

[Anand Buddhdev]

Hello BIND developers,

I've updated from BIND 9.10 to 9.11, and noticed the following happening
whenever "rndc reconfig" is run:

05-Aug-2017 11:11:42.066 general: received control channel command
'reconfig'
05-Aug-2017 11:11:42.066 general: loading configuration from
'/etc/named/named.conf'
...
...
05-Aug-2017 11:11:42.525 general: zone 116.195.in-addr.arpa/IN/main:
loaded serial 2017020301
05-Aug-2017 11:11:42.525 general: zone 116.195.in-addr.arpa/IN/main: expired
05-Aug-2017 11:11:42.533 general: zone egouv.ci/IN/main: loaded serial
2017062009
05-Aug-2017 11:11:42.606 general: zone 232.128.in-addr.arpa/IN/main:
loaded serial 2017071557 (DNSSEC signed)
05-Aug-2017 11:11:42.638 general: zone 43.137.in-addr.arpa/IN/main:
loaded serial 2017071100
05-Aug-2017 11:11:42.638 general: zone 43.137.in-addr.arpa/IN/main: expired
05-Aug-2017 11:11:42.639 general: any newly configured zones are now loaded
05-Aug-2017 11:11:42.639 general: zone egouv.ci/IN/main: expired
05-Aug-2017 11:11:42.646 general: zone 232.128.in-addr.arpa/IN/main: expired
05-Aug-2017 11:11:42.659 general: running

For a moment, BIND loads expired zones, and even answers queries for
them, and then sets their state back to expired. This didn't happen on
9.10, but has been happening on 9.11. Is there a reason this behaviour
has changed?

Regards,
Anand