autosign conversion from NSEC3 to NSEC can take more than 2 seconds.

Job #636967 failed for 891f24fa:

I:autosign:checking NSEC3->NSEC conversion with 'rndc signing -nsec3param none' (18)
I:autosign:failed

echo_i "checking NSEC3->NSEC conversion with 'rndc signing -nsec3param none' ($n)"
ret=0
$RNDCCMD 10.53.0.3 signing -nsec3param none autonsec3.example. > /dev/null 2>&1
sleep 2
# this command should result in an empty file:
$DIG $DIGOPTS +noall +answer autonsec3.example. nsec3param @10.53.0.3 > dig.out.ns3.nx.test$n || ret=1
grep "NSEC3PARAM" dig.out.ns3.nx.test$n > /dev/null && ret=1

05-Feb-2020 07:48:14.119 received control channel command 'signing -nsec3param none autonsec3.example.'

05-Feb-2020 07:48:16.135 query client=0x7f3f0c0029f0 thread=0x7f3f27436700 (autonsec3.example/NSEC3PARAM): qctx_init

05-Feb-2020 07:48:16.215 setnsec3param: zone autonsec3.example/IN: enter

05-Feb-2020 07:48:16.219 del autonsec3.example. 0       IN      NSEC3PARAM 1 0 10 BEEF