Reference counting failure "REQUIRE(ptr != ((void *)0))" in db.c

Job #3368111 failed for 9b282256.

ns3 of the inline test hit a reference counting issue REQUIRE(ptr != ((void *)0)) in db.c.

D:/builds/isc-projects/bind9/bin/tests/system/inline:Core was generated by `/builds/isc-projects/bind9/bin/named/.libs/named -D inline-ns3 -X named.lock -m'.
D:/builds/isc-projects/bind9/bin/tests/system/inline:Program terminated with signal SIGABRT, Aborted.
D:/builds/isc-projects/bind9/bin/tests/system/inline:#0  __pthread_kill_implementation (threadid=<optimized out>, signo=signo@entry=6, no_tid=no_tid@entry=0) at ./nptl/pthread_kill.c:44
D:/builds/isc-projects/bind9/bin/tests/system/inline:[Current thread is 1 (Thread 0x7f6719e53680 (LWP 1823))]
D:/builds/isc-projects/bind9/bin/tests/system/inline:#0  __pthread_kill_implementation (threadid=<optimized out>, signo=signo@entry=6, no_tid=no_tid@entry=0) at ./nptl/pthread_kill.c:44
D:/builds/isc-projects/bind9/bin/tests/system/inline:#1  0x00007f67205f5d2f in __pthread_kill_internal (signo=6, threadid=<optimized out>) at ./nptl/pthread_kill.c:78
D:/builds/isc-projects/bind9/bin/tests/system/inline:#2  0x00007f67205a6ef2 in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26
D:/builds/isc-projects/bind9/bin/tests/system/inline:#3  0x00007f6720591472 in __GI_abort () at ./stdlib/abort.c:79
D:/builds/isc-projects/bind9/bin/tests/system/inline:#4  0x000055a4e5ebb96a in assertion_failed (file=<optimized out>, line=150, type=isc_assertiontype_require, cond=0x7f67211a7b8d "ptr != ((void *)0)") at main.c:225
D:/builds/isc-projects/bind9/bin/tests/system/inline:#5  0x00007f672121f29a in isc_assertion_failed (file=file@entry=0x7f672118d510 "db.c", line=line@entry=150, type=type@entry=isc_assertiontype_require, cond=cond@entry=0x7f67211a7b8d "ptr != ((void *)0)") at assertions.c:48
D:/builds/isc-projects/bind9/bin/tests/system/inline:#6  0x00007f6721011801 in dns_db_ref (ptr=<optimized out>) at db.c:150
D:/builds/isc-projects/bind9/bin/tests/system/inline:#7  0x00007f67210118ad in dns_db_attach (ptr=0x0, ptrp=ptrp@entry=0x7f6719e51f90) at db.c:150
D:/builds/isc-projects/bind9/bin/tests/system/inline:#8  0x00007f6721169559 in zone_resigninc (zone=zone@entry=0x55a4e64d2710) at zone.c:6828
D:/builds/isc-projects/bind9/bin/tests/system/inline:#9  0x00007f672117214f in zone_maintenance (zone=<optimized out>) at zone.c:11100
D:/builds/isc-projects/bind9/bin/tests/system/inline:#10 0x00007f67211750e6 in zone_timer (arg=<optimized out>) at zone.c:14634
D:/builds/isc-projects/bind9/bin/tests/system/inline:#11 0x00007f672124776e in timer_cb (handle=<optimized out>) at timer.c:111
D:/builds/isc-projects/bind9/bin/tests/system/inline:#12 0x00007f6720a35cbe in ?? () from /lib/x86_64-linux-gnu/libuv.so.1
D:/builds/isc-projects/bind9/bin/tests/system/inline:#13 0x00007f6720a3999f in uv_run () from /lib/x86_64-linux-gnu/libuv.so.1
D:/builds/isc-projects/bind9/bin/tests/system/inline:#14 0x00007f6721234748 in loop_thread (arg=arg@entry=0x55a4e613b4b8) at loop.c:311
D:/builds/isc-projects/bind9/bin/tests/system/inline:#15 0x00007f6721246012 in thread_body (wrap=0x55a4e61782f0) at thread.c:89
D:/builds/isc-projects/bind9/bin/tests/system/inline:#16 thread_run (wrap=0x55a4e61782f0) at thread.c:104
D:/builds/isc-projects/bind9/bin/tests/system/inline:#17 0x00007f67205f3fd4 in start_thread (arg=<optimized out>) at ./nptl/pthread_create.c:442
D:/builds/isc-projects/bind9/bin/tests/system/inline:#18 0x00007f6720673820 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:100

It seems that named crashed shortly before the testing that inline signing works with inactive ZSK and active KSK test.

CI artifacts were saved in the job.