Wait for mirror zone to be deleted

Job #589745 failed for 1c371c1d:

I:mirror:checking that a mirror zone can be deleted using rndc (28)
I:mirror:failed
I:mirror:exit status: 1
R:mirror:FAIL
E:mirror:Tue Jan 21 22:28:27 UTC 2020

n=`expr $n + 1`
echo_i "checking that a mirror zone can be deleted using rndc ($n)"
ret=0
# Remove the mirror zone added in the previous test.
$RNDCCMD 10.53.0.3 delzone verify-addzone > rndc.out.ns3.test$n 2>&1 || ret=1
# Check whether the mirror zone was removed.
$DIG $DIGOPTS @10.53.0.3 +norec verify-addzone SOA > dig.out.ns3.test$n 2>&1 || ret=1
grep "NXDOMAIN" dig.out.ns3.test$n > /dev/null || ret=1
grep "flags:.* aa" dig.out.ns3.test$n > /dev/null && ret=1
grep "flags:.* ad" dig.out.ns3.test$n > /dev/null || ret=1
if [ $ret != 0 ]; then echo_i "failed"; fi
status=`expr $status + $ret`

21-Jan-2020 22:28:23.184 received control channel command 'delzone verify-addzone'

21-Jan-2020 22:28:26.422 zone verify-addzone/IN: mirror zone is no longer in use; reverting to normal recursion

21-Jan-2020 22:28:26.422 shutting down

21-Jan-2020 22:28:26.425 client @0x7f59b8010370 10.53.0.1#34239: no matching view in class 'IN'
21-Jan-2020 22:28:26.425 client @0x7f59b8010370 10.53.0.1#34239: no matching view in class
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id:  24320
;; flags: ad; QUESTION: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags: do; udp: 4096
; COOKIE: cde32bbbac68a62b
;; QUESTION SECTION:
;verify-addzone.                        IN      SOA


21-Jan-2020 22:28:26.425 client @0x7f59b8010370 10.53.0.1#34239: error
21-Jan-2020 22:28:26.425 client @0x7f59b8010370 10.53.0.1#34239: send
21-Jan-2020 22:28:26.425 client @0x7f59b8010370 10.53.0.1#34239: sendto
21-Jan-2020 22:28:26.425 client @0x7f59b8010370 10.53.0.1#34239: senddone
21-Jan-2020 22:28:26.425 client @0x7f59b8010370 10.53.0.1#34239: next
21-Jan-2020 22:28:26.425 client @0x7f59b8010370 10.53.0.1#34239: endrequest