named doesn't shut down after receiving rndc stop command

shutdown system tests #3376811 and #3376814 failed:

D:shutdown:                if remaining <= 0:
D:shutdown:>                   raise TimeoutExpired(self.args, timeout)
D:shutdown:E                   subprocess.TimeoutExpired: Command '['/builds/isc-projects/bind9/bin/rndc/rndc', '-c', '../common/rndc.conf', '-p', '14630', '-s', '10.53.0.3', 'status']' timed out after 10 seconds
...
D:shutdown:----------------------------- Captured stderr call -----------------------------
D:shutdown:rndc: recv failed: connection reset

!7819 (merged) might be somehow the culprit.