Don't know whether this is the same bug... here are 2
crashdumps which look related. (from end of last week)

#7  0xc037d16a in kdb_trap ()
#8  0xc038a4f0 in trap ()
#9  0xc0103029 in calltrap ()
#10 0xc02cc311 in sa_switchcall ()

#7  0xc037d16a in kdb_trap ()
#8  0xc038a4f0 in trap ()
#9  0xc0103029 in calltrap ()
#10 0xc036dd0e in uvmspace_free ()
#11 0xc02bf289 in exit1 ()
#12 0xc02bf047 in sys_exit ()
#13 0xc0389f53 in syscall_plain ()

best regards
Matthias