ThreadSanitizer: data race - lib/dns/tests/zt_test

lib/dns/tests/zt_test failed

WARNING: ThreadSanitizer: data race 
  Write of size 8 at 0x000000000001 by main thread (mutexes: write M1, write M2):
    #0 free <null>
    #1 default_memfree lib/isc/mem.c:713:2
    #2 mem_put lib/isc/mem.c:627:2
    #3 isc___mem_putanddetach lib/isc/mem.c:960:3
    #4 isc__mem_putanddetach lib/isc/mem.c:2380:2
    #5 zt_destroy lib/dns/zt.c:233:2
    #6 zt_flushanddetach lib/dns/zt.c:250:3
    #7 dns_zt_detach lib/dns/zt.c:261:2
    #8 view_flushanddetach lib/dns/view.c:594:5
    #9 dns_view_detach lib/dns/view.c:635:2
    #10 asyncload_zt lib/dns/tests/zt_test.c:339:2
    #11 <null> <null>
    #12 __libc_start_main <null>

  Previous atomic write of size 8 at 0x000000000001 by thread T1:
    #0 __tsan_atomic64_fetch_sub <null>
    #1 doneloading lib/dns/zt.c:551:6
    #2 zone_asyncload lib/dns/zone.c:2201:3
    #3 dispatch lib/isc/task.c:1134:7
    #4 run lib/isc/task.c:1319:2

  Mutex M1 (0x000000000020) created at:
    #0 pthread_mutex_init <null>
    #1 isc__mutex_init lib/isc/pthreads/mutex.c:284:8
    #2 dns_view_create lib/dns/view.c:107:2
    #3 dns_test_makeview lib/dns/tests/dnstest.c:225:2
    #4 dns_test_makezone lib/dns/tests/dnstest.c:273:12
    #5 asyncload_zt lib/dns/tests/zt_test.c:275:11
    #6 <null> <null>
    #7 __libc_start_main <null>

  Mutex M2 (0x000000000027) created at:
    #0 pthread_mutex_init <null>
    #1 isc__mutex_init lib/isc/pthreads/mutex.c:284:8
    #2 mem_create lib/isc/mem.c:737:2
    #3 isc_mem_create lib/isc/mem.c:2358:2
    #4 dns_test_begin lib/dns/tests/dnstest.c:145:2
    #5 _setup lib/dns/tests/zt_test.c:55:11
    #6 <null> <null>
    #7 __libc_start_main <null>

  Thread T1 (running) created by main thread at:
    #0 pthread_create <null>
    #1 isc_thread_create lib/isc/pthreads/thread.c:75:8
    #2 isc_taskmgr_create lib/isc/task.c:1410:3
    #3 create_managers lib/dns/tests/dnstest.c:119:2
    #4 dns_test_begin lib/dns/tests/dnstest.c:180:3
    #5 _setup lib/dns/tests/zt_test.c:55:11
    #6 <null> <null>
    #7 __libc_start_main <null>

SUMMARY: ThreadSanitizer: data race in free