Recursive-clients 0 triggers an assertion

recursive-clients 0; in 9.20+ triggers an assertion at startup.

Thread 0 Crashed::  Dispatch queue: com.apple.main-thread
0   libsystem_kernel.dylib        	       0x182dd4704 __pthread_kill + 8
1   libsystem_pthread.dylib       	       0x182e0bc28 pthread_kill + 288
2   libsystem_c.dylib             	       0x182d19ae8 abort + 180
3   named                         	       0x1000566f8 assertion_failed + 328 (main.c:231)
4   libisc-9.21.3-dev.dylib       	       0x100247644 isc_assertion_failed + 56 (assertions.c:48)
5   libisc-9.21.3-dev.dylib       	       0x10027c928 isc_quota_soft + 164 (quota.c:39)
6   named                         	       0x10006faa8 load_configuration + 2636 (server.c:8207)
7   named                         	       0x10005c590 run_server + 552 (server.c:9624)
8   libisc-9.21.3-dev.dylib       	       0x100247bd0 isc__async_cb + 440 (async.c:111)
9   libuv.1.dylib                 	       0x10042a3c4 uv__async_io + 320
10  libuv.1.dylib                 	       0x10043a1e0 uv__io_poll + 1748
11  libuv.1.dylib                 	       0x10042a7bc uv_run + 244
12  libisc-9.21.3-dev.dylib       	       0x1002697d8 loop_thread + 608 (loop.c:327)
13  libisc-9.21.3-dev.dylib       	       0x100288b34 thread_body + 88 (thread.c:85)
14  libisc-9.21.3-dev.dylib       	       0x100288aac isc_thread_main + 104 (thread.c:116)
15  libisc-9.21.3-dev.dylib       	       0x100269448 isc_loopmgr_run + 472 (loop.c:513)
16  named                         	       0x1000564b8 main + 528 (main.c:1531)
17  dyld                          	       0x182ab3fd8 start + 2412