exclusive sleep mutex ifnet r = 0 (0xc07cc940) locked @ net/if.c:459

Updated to HEAD, booted with WITNESS enabled, and the boot dies here:

ipfw2 initialized, divert disabled, rule-based forwarding enabled, default to accept, logging unlimited
malloc() of "16" with the following non-sleepable locks held:
exclusive sleep mutex ifnet r = 0 (0xc07cc940) locked _at_ net/if.c:459
Debugger("witness_warn")
Stopped at      Debugger+0x54:  xchgl   %ebx,in_Debugger.0
db> trace
Debugger(c070f058,c0c21ce8,1,c07396e3,c0778ec0) at Debugger+0x54
witness_warn(5,0,c074cdc7,c072620e,c07cc940) at witness_warn+0x19f
uma_zalloc_arg(c103a900,0,2,0,c07cce74) at uma_zalloc_arg+0xa0
malloc(10,c0778ec0,2,1c,c077d100) at malloc+0xd3
in6_domifattach(c4742000,8c,c4742000,c07843f0,c26000) at in6_domifattach+0x27
if_attachdomain1(c4742000,0,c073e7c3,1cb,c0755fa4) at if_attachdomain1+0x3e
if_attachdomain(0,c1e000,c1ec00,c1e000,0) at if_attachdomain+0x48
mi_startup() at mi_startup+0xb5
begin() at begin+0x2c

Can you please investigate?

Kris