pkgbase and customised builds via ${SRC}/release/release.sh

Hello,

For years, I have been using one host to build all customised USB
images, and tarballs for all other hosts at home. This is reached via
custom make, and src.conf files, which are codified in a custom
release.conf. My custom release.conf redefines load_chroot_env() to
setup the environment with ${SRC}, ${PORTS}, and pkg related files.

On 16-CURRENT (2-3 weeks behind) I am able to use
${SRC}/release/release.sh sans customisation, however, when I start to
introduce customisations, the build never succeeds. At the moment, the
build fails at:

make[5]: stopped making "create-kernel-packages" in /usr/src
make[5]: stopped making "create-world-packages" in /usr/src
make[5]: stopped making "create-world-packages" in /usr/src
make[4]: stopped making "real-packages" in /usr/src
make[5]: stopped making "create-kernel-packages" in /usr/src
make[4]: stopped making "real-packages" in /usr/src
make[4]: stopped making "real-packages" in /usr/src
make[3]: stopped making "real-packages" in /usr/src
make[2]: stopped making "packages" in /usr/src
make[2]: stopped making "packages" in /usr/src
make[1]: stopped making "packages" in /usr/src
make[1]: stopped making "packages" in /usr/src
make: stopped making "release" in /usr/src/release
make: stopped making "release" in /usr/src/release
pkg: Unable to open plist file:
/usr/obj/usr/src/amd64.amd64/kernelstage/kernel/kernel.FAFNIR-dbg.plist

I have no debug enabled options, and am not interested in debug builds.
In the past, when I needed debug features, I would edit the kernel
config, and src.conf files, and start the release build process from
there; I do not know how to parametrise debug build options.

What is the method for using release.sh to custom build a pkgbase, that
also supports tarballs, and install images?

--
To good health, and happy holidays
Alastair