"*** [kernel.debug] Error code 139"?

During an attempt to build & install a GENERIC i386 kernel _at_r276775
(while running head/i386 _at_r276694), I encountered the above; more
context:

...
--- vers.o ---
cc  -c -O -pipe  -g -Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes
  -Wmissing-prototypes -Wpointer-arith -Winline -Wcast-qual  -Wundef -Wno-pointe
r-sign -fformat-extensions  -Wmissing-include-dirs -fdiagnostics-show-option  -W
no-unknown-pragmas  -Wno-error-tautological-compare -Wno-error-empty-body  -Wno-
error-parentheses-equality -Wno-error-unused-function  -Wno-error-pointer-sign -
Wno-error-format -Wno-error-parentheses -nostdinc  -I. -I/usr/src/sys -I/usr/src
/sys/contrib/altq -I/usr/src/sys/contrib/libfdt -D_KERNEL -DHAVE_KERNEL_OPTION_H
EADERS -include opt_global.h  -mno-mmx -mno-sse -msoft-float -ffreestanding -fst
ack-protector -gdwarf-2 -Wno-error-tautological-compare -Wno-error-empty-body  -
Wno-error-parentheses-equality -Wno-error-unused-function  -Wno-error-pointer-si
gn -Wno-error-format -Wno-error-parentheses -Wall -Wredundant-decls -Wnested-ext
erns -Wstrict-prototypes  -Wmissing-prototypes -Wpointer-arith -Winline -Wcast-q
ual  -Wundef -Wno-pointer-sign -fformat-extensions  -Wmissing-include-dirs -fdia
gnostics-show-option  -Wno-unknown-pragmas  -Wno-error-tautological-compare -Wno
-error-empty-body  -Wno-error-parentheses-equality -Wno-error-unused-function  -
Wno-error-pointer-sign -Wno-error-format -Wno-error-parentheses  -mno-aes -mno-a
vx  -std=iso9899:1999 -Werror  vers.c
ctfconvert -L VERSION -g vers.o
--- kernel.debug ---
linking kernel.debug
ctfmerge -L VERSION -g -o kernel.debug ...
Segmentation fault (core dumped)
*** [kernel.debug] Error code 139

bmake: stopped in /common/S4/obj/usr/src/sys/GENERIC
1 error

bmake: stopped in /common/S4/obj/usr/src/sys/GENERIC
*** [buildkernel] Error code 2

bmake: stopped in /usr/src
1 error
....


src.conf is empty; make.conf merely has:
SENDMAIL_MC=/etc/mail/client.mc

I puzzled over it for a bit, then re-ran the "make -DNOCLEAN -j4
buildkernel" -- and the second time around, there were no complaints;
the machine is now running:

FreeBSD freebeast.catwhisker.org 11.0-CURRENT FreeBSD 11.0-CURRENT #1712  r276775M/276775:1100052: Wed Jan  7 05:09:01 PST 2015     root_at_freebeast.catwhisker.org:/common/S4/obj/usr/src/sys/GENERIC  i386

My laptop didn't encounter the issue (and is installing its kernel
as I type).

I'm mostly wondering what "Error code 139" is intended to mean.... :-}

Peace,
david
-- 
David H. Wolfskill				david_at_catwhisker.org
Actions have consequences ... as do inactions.

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