CUURENT: Cross-build for 11.1-RELENG (base packages) fails: *** [create-kernel-packages] Error code 70

Recently, building 11.1-RELENG soruces on CURRENT (most recent on amd64) start
failing with an obscure error, shown below. Is this something I need to take
care of in make.conf, src.conf or anywere elese?


Thanks in advance,

Oliver

[...]
===> Creating FreeBSD-kernel-generic-11.1_6
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 ===> Creating
FreeBSD-kernel-generic-debug-11.1_6 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 open plist
file: /pool/sources/11.1-RELENG/obj/pool/sources/11.1-RELENG/src/amd64.amd64/kernelstage/kernel/kernel.GENERIC-debug.plist
*** [create-kernel-packages] Error code 70

make[5]: stopped in /pool/sources/11.1-RELENG/src
1 error

make[5]: stopped in /pool/sources/11.1-RELENG/src
*** [create-kernel-packages] Error code 2