Poudriere failed to build pkg in 13-stable jail under 12-stable

[Thomas Legg]

The build of a 13-stable source and kernel were a success under 12-stable
(though with some issues on freeze-ups and hard reboots that I suspect
might be related to the bufdaemon issue and my 0x15 gen AMD cpu).

Created a 13-stable poudriere jail with the knowledge that there may be
issues with builds under a 12-stable r369076 kernel. I didn't expect this
failure on packaging pkg.

====> Compressing man pages (compress-man)
===>   Installing ldconfig configuration file
===========================================================================
=======================<phase: package        >============================
===>  Building package for pkg-1.16.2
cp: /wrkdirs/usr/ports/ports-mgmt/pkg/work/pkg/pkg-1.16.2.txz: Function not
implemented
*** Error code 1

Stop.
make[1]: stopped in /usr/ports/ports-mgmt/pkg
*** Error code 1

Stop.
make: stopped in /usr/ports/ports-mgmt/pkg
=>> Cleaning up wrkdir
===>  Cleaning for pkg-1.16.2
build of ports-mgmt/pkg | pkg-1.16.2 ended at Mon Jan 25 12:16:12 HKT 2021
build time: 00:02:01
!!! build failure encountered !!!