build command ./build.sh -j3 -x release

releasedir has indeed not yet been created in /usr/obj

--- netbsd ---
# link INSTALL_XENU/netbsd
/usr/src/obj/tooldir.NetBSD-3.99.15-i386/bin/i386--netbsdelf-ld -T / 
usr/src/sys/arc/i386/conf/kern.ldscript -Ttext c01000000 -e start -X - 
o netbsd ${SYSTEM_OBJ} ${EXTRA_OBJ} vers.o
text data bss dec hex filename
1367002 5145800 133004 6656806 65682e netbsd
sync
--- kernset-GENERIC ---
echo netbsd | GZIP=0- /usr/src/obj/tooldir.NetBSD-3.99.15-i386/bin/ 
nbpax -O -zw -M -N /usr/src/etc -f /usr/src/obj/releasedir/i386/ 
binary/sets/kern-GENERIC.tgz
pax: Failed open to write on /usr/src/obj/releasedir/i386/binary/sets/ 
kern-GENERIC.tgz (No such file or directory)
*** [kernset-GENERIC] Error code 1
1 error

nbmake: stopped in /usr/src/etc
*** [release] Error code 2
1 error

nbmake: stopped in /usr/src

ERROR: filed to make release
*** BUILD ABORTED ***