crash in 9.14.2, possibly on shutdown, cannot reproduce

Updating from 9.14.1 to 9.14.2, scripts here do a few shutdown/restarts of bind. I cannot reproduce this.

(gdb) bt
#0  0x0000003a210324f5 in raise () from /lib64/libc.so.6
#1  0x0000003a21033cd5 in abort () from /lib64/libc.so.6
#2  0x000000000041e483 in assertion_failed (file=<value optimized out>, line=<value optimized out>, type=<value optimized out>, 
    cond=<value optimized out>) at ./main.c:253
#3  0x00007f8acaa1b23a in isc_assertion_failed (file=<value optimized out>, line=<value optimized out>, type=<value optimized out>, 
    cond=<value optimized out>) at assertions.c:50
#4  0x00007f8acaa2da9b in isc_mempool_destroy (mpctxp=0x7f8abc6c4e20) at mem.c:1647
#5  0x00007f8abc3adb59 in plugin_destroy (instp=0x7f8ac40c3e30) at filter-aaaa.c:456
#6  0x00007f8acb6df4b2 in unload_plugin (pluginp=<value optimized out>) at hooks.c:238
#7  0x00007f8acb6df5ca in ns_plugins_free (mctx=0x211d210, listp=<value optimized out>) at hooks.c:553
#8  0x00007f8acb406465 in destroy (view=0x7f8ac01872e0) at view.c:559
#9  0x00007f8acb42086e in zone_free (zone=0x7f8ac0b66d70) at zone.c:1135
#10 0x00007f8acb429d90 in zone_shutdown (task=<value optimized out>, event=<value optimized out>) at zone.c:13311
#11 0x00007f8acaa3b8b7 in dispatch (queuep=<value optimized out>) at task.c:1130
#12 run (queuep=<value optimized out>) at task.c:1297
#13 0x0000003a21407aa1 in start_thread () from /lib64/libpthread.so.0
#14 0x0000003a210e8c4d in clone () from /lib64/libc.so.6