dhclient fails: can't open and lock /var/db/dhclient.leases.wlan0: Bad file descriptor

This was head _at_r313544; previous successful build/smoke test was
_at_r313467 (yesterday).

Here's an excerpt from a typescript I made of some "poking around";
subsequent to that, I was able to set the IP address, netmask, and
broadcast address on the NIC (wlano), then set the default route, and
once that was done, I was able to use the network:

wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        ether 00:24:d6:7a:03:ce
        inet 0.0.0.0 netmask 0xff000000 broadcast 255.255.255.255 
        nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
        media: IEEE 802.11 Wireless Ethernet MCS mode 11ng
        status: associated
        ssid lmdhw-net channel 1 (2412 MHz 11g ht/20) bssid 04:18:d6:22:22:1f
        regdomain FCC country US authmode WPA2/802.11i privacy ON
        deftxkey UNDEF AES-CCM 2:128-bit txpower 30 bmiss 10 scanvalid 60
        protmode CTS ampdulimit 64k ampdudensity 8 -amsdutx amsdurx shortgi
        -stbc -ldpc wme roaming MANUAL
        groups: wlan 
(12.0-C)[4] pgrep dhclient
(12.0-C)[5] dhclient wlan0
dhclient: /etc/dhclient-enter-hooks invoked with reason PREINIT
dhclient: Leaving hostname set to 
dhclient: /etc/dhclient-exit-hooks invoked with reason PREINIT
dhclient: reason was PREINIT; no action taken
dhclient: Exiting /etc/dhclient-exit-hooks (PREINIT) with exit_status 0
can't open and lock /var/db/dhclient.leases.wlan0: Bad file descriptor
exiting.
(12.0-C)[6] ls -lTio /var/db/dhclient.leases*
883105 ----------  1 root  wheel  - 4017 Jan  4 09:18:10 2017 /var/db/dhclient.leases.em0
883280 ----------  1 root  wheel  -  856 Aug 11 04:52:54 2015 /var/db/dhclient.leases.lagg0
883344 ----------  1 root  wheel  - 3333 Jan 20 21:19:10 2015 /var/db/dhclient.leases.vboxnet0
883108 ----------  1 root  wheel  - 1993 Feb 10 04:30:13 2017 /var/db/dhclient.leases.wlan0
883079 ----------  1 root  wheel  - 2013 Jan 19 11:52:07 2017 /var/db/dhclient.leases.wlan1


Moving /var/db/dhclient.leases.wlan0 aside did not change the behavior.

Stable/11 shows the iwn(4) device as:
g1-252(11.0-S)[4] pciconf -lv | grep -A 3 iwn
iwn0_at_pci0:3:0:0:        class=0x028000 card=0x13218086 chip=0x42328086 rev=0x00 hdr=0x00
    vendor     = 'Intel Corporation'
    device     = 'WiFi Link 5100'
    class      = network
g1-252(11.0-S)[5] 

File system for /var is a fairly vanilla UFS2+SU.  I suppose I could have
tried ktrace (had I thought of it before switching back to the stable/11
slice).

Peace,
david
-- 
David H. Wolfskill				david_at_catwhisker.org
How could one possibly "respect" a misogynist, racist, bullying con-man??!?

See http://www.catwhisker.org/~david/publickey.gpg for my public key.