make release failures on releng/15.0 branch

[Sad Clouds]

Hello, there seems to be something wrong with the release target. This
used to work correctly with older releases. I'm building this on 14.3.
Any ideas?

# Build everything
cd ${FREEBSD_SRC:?} && env \
MAKEOBJDIRPREFIX=${FREEBSD_OBJ:?} SRCCONF="${BUILD_DIR:?}/src.conf" SYSDIR="${FREEBSD_SRC:?}/sys" \
make TARGET=${MACHINE:?} TARGET_ARCH=${MACHINE_ARCH:?} \
-j 24 buildworld buildkernel > ${BUILD_DIR:?}/build.log 2>&1

# Create release
cd ${FREEBSD_SRC:?}/release && env \
MAKEOBJDIRPREFIX=${FREEBSD_OBJ:?} SRCCONF="${BUILD_DIR:?}/src.conf" SYSDIR="${FREEBSD_SRC:?}/sys" \
make TARGET=${MACHINE:?} TARGET_ARCH=${MACHINE_ARCH:?} \
-j 24 release > ${BUILD_DIR:?}/release.log 2>&1

less release.log

pkg: No packages available to install matching 'pkg' have been found in the repositories
*** [bootonly] Error code 1

make: stopped in /freebsd/src/release
--- disc1 ---
/usr/libexec/flua: /freebsd/src/release/scripts/pkgbase-stage.lua:49: assertion failed!
stack traceback:
[C]: in function 'assert'
/freebsd/src/release/scripts/pkgbase-stage.lua:49: in upvalue 'select_packages'
/freebsd/src/release/scripts/pkgbase-stage.lua:101: in local 'main'
/freebsd/src/release/scripts/pkgbase-stage.lua:107: in main chunk
[C]: in ?
*** [disc1] Error code 1

make: stopped in /freebsd/src/release
2 errors