FreeBSD-base: build 11-STABLE on 12-CURRENT host system

I do not know whether this is the correct list, but since FreeBSD-base support
(updating the OS via pkg as a feature) is considered BETA in FBSD 11, it is
best to address the CURRENT list. Sorry if I'm mislead.

The problem is, I try to build a "repo" on a 12-CURRENT host (r319846)
with a dedicated 11-STABLE source tree (at the moment at r319892). It doesn't
work, the creation of packages fail with the error shown below. It seems some
targets are missing and I suspect the divergence between host OS and the
supposed target OS (11-STABLE) as the warning "Major
OS version upgrade detected" indicates.

I provide you with these variables/environment setting I use:

RELCONFBASE=/pool/relconfig/11/ 		#outside chroot()!
__MAKE_CONF=${RELCONFBASE}/etc/make.conf
SRCCONF=${RELCONFBASE}/etc/src.conf
SRC_ENV_CONF=${RELCONFBASE}/etc/src-env.conf
NO_INSTALLEXTRAKERNELS=NO
KERNCONFDIR=${RELCONFBASE}/kernel_conf/amd64/
KERNCONF="MONITOR GENERIC2"

and the build itself:

cd ${SRCBASE}/src ;
env MAKEOBJDIRPREFIX=${SRCBASE}/obj/ \
make  \
__MAKE_CONF=${__MAKE_CONF} \
SRCCONF=${SRCCONF} \
SRC_ENV_CONF=${SRC_ENV_CONF} \
KERNCONFDIR=${KERNCONFDIR} \
KERNCONF="${KERNCONF}" \
NO_INSTALLEXTRAKERNELS=NO \
${MKPARALLEL} \
buildworld buildkernel

So far, this works with all desired aspects.

But the make-target "packages" fails then as shown below.

I use the very same schematics of a setup with TARGET=arm64 for crosscompiling
12-CURRENT for arm64.aarch64, which runs up to the end very smooth - so, again,
the suspect is the diifference between the major OS versions.

I's like to know how to build a 11-STABLE or, in the near future, the
11.1-RELENG FreeBSD-base repository on a 12-CURRENT platform. Is this possible
in pricinciple (I think yes, but ...)? 

Or is there something I have missed?

Thanks in advance,

Oliver Hartmann

[...]
install -U
-M /pool/sources/11-STABLE//obj//pool/sources/11-STABLE/src/amd64.amd64/kernelstage//kernel.GENERIC2.premeta
-D /pool/sources/11-STABLE/obj/pool/sources/11-STABLE/src/amd64.amd64/kernelstage
-T release -o root -g wheel -m 555
zlib.ko /pool/sources/11-STABLE/obj/pool/sources/11-STABLE/src/amd64.amd64/kernelstage/kernel.GENERIC2/boot/kernel.GENERIC2/
kldxref /pool/sources/11-STABLE/obj/pool/sources/11-STABLE/src/amd64.amd64/kernelstage/kernel.GENERIC2/boot/kernel.GENERIC2
--- create-packages --- --- create-world-packages --- --- create-world-packages
--- ===> Creating FreeBSD-acct-11.1 pkg: Warning: Major OS version upgrade
detected.  Running "pkg-static install -f pkg" recommended pkg: Warning: Major
OS version upgrade detected.  Running "pkg-static install -f pkg" recommended
pkg: Unable to access
file /pool/sources/11-STABLE//obj//pool/sources/11-STABLE/src/amd64.amd64/worldstage/pool/sources/11-STABLE//obj//pool/sources/11-STABLE/src/amd64.amd64/worldstage/etc/periodic/daily/310.accounting:No
such file or directory pkg: Unable to access
file /pool/sources/11-STABLE//obj//pool/sources/11-STABLE/src/amd64.amd64/worldstage/pool/sources/11-STABLE//obj//pool/sources/11-STABLE/src/amd64.amd64/worldstage/etc/periodic/monthly/200.accounting:No
such file or directory pkg: Unable to access
file /pool/sources/11-STABLE//obj//pool/sources/11-STABLE/src/amd64.amd64/worldstage/pool/sources/11-STABLE//obj//pool/sources/11-STABLE/src/amd64.amd64/worldstage/etc/rc.d/accounting:No
such file or directory pkg: Unable to access
file /pool/sources/11-STABLE//obj//pool/sources/11-STABLE/src/amd64.amd64/worldstage/pool/sources/11-STABLE//obj//pool/sources/11-STABLE/src/amd64.amd64/worldstage/usr/bin/lastcomm:No
such file or directory pkg: Unable to access
file /pool/sources/11-STABLE//obj//pool/sources/11-STABLE/src/amd64.amd64/worldstage/pool/sources/11-STABLE//obj//pool/sources/11-STABLE/src/amd64.amd64/worldstage/usr/share/man/man1/lastcomm.1.gz:No
such file or directory pkg: Unable to access
file /pool/sources/11-STABLE//obj//pool/sources/11-STABLE/src/amd64.amd64/worldstage/pool/sources/11-STABLE//obj//pool/sources/11-STABLE/src/amd64.amd64/worldstage/usr/sbin/accton:No
such file or directory pkg: Unable to access
file /pool/sources/11-STABLE//obj//pool/sources/11-STABLE/src/amd64.amd64/worldstage/pool/sources/11-STABLE//obj//pool/sources/11-STABLE/src/amd64.amd64/worldstage/usr/share/man/man8/accton.8.gz:No
such file or directory pkg: Unable to access
file /pool/sources/11-STABLE//obj//pool/sources/11-STABLE/src/amd64.amd64/worldstage/pool/sources/11-STABLE//obj//pool/sources/11-STABLE/src/amd64.amd64/worldstage/usr/sbin/sa:No
such file or directory pkg: Unable to access
file /pool/sources/11-STABLE//obj//pool/sources/11-STABLE/src/amd64.amd64/worldstage/pool/sources/11-STABLE//obj//pool/sources/11-STABLE/src/amd64.amd64/worldstage/usr/share/man/man8/sa.8.gz:No
such file or directory *** [create-world-packages] Error code 70
[...]